Revert "Error on missing method implementation in non-abstract class"

This reverts commit 7cc55d0372. Reason for revert: More test fixes needed. Change-Id: Ib36159184ffbd14ce3f7cca184ce2b8cdfec237c Reviewed-on: https://dart-review.googlesource.com/51680 Reviewed-by: Aske Simon Christensen <askesc@google.com> Commit-Queue: Aske Simon Christensen <askesc@google.com>
2024-09-16 00:29:48 +00:00 · 2018-04-18 17:27:22 +00:00 · 2018-04-18 17:27:22 +00:00 · 2b09c1efc0
parent 7cc55d0372
commit 2b09c1efc0
168 changed files with 456 additions and 899 deletions
--- a/pkg/analyzer/lib/src/fasta/error_converter.dart
+++ b/pkg/analyzer/lib/src/fasta/error_converter.dart
@ -64,12 +64,6 @@ class FastaErrorReporter {
        errorReporter?.reportErrorForOffset(
            ParserErrorCode.COLON_IN_PLACE_OF_IN, offset, length);
        return;
-      case "CONCRETE_CLASS_WITH_ABSTRACT_MEMBER":
-        errorReporter?.reportErrorForOffset(
-            StaticWarningCode.CONCRETE_CLASS_WITH_ABSTRACT_MEMBER,
-            offset,
-            length);
-        return;
      case "CONST_AFTER_FACTORY":
        errorReporter?.reportErrorForOffset(
            ParserErrorCode.CONST_AFTER_FACTORY, offset, length);
--- a/pkg/front_end/lib/src/fasta/fasta_codes_generated.dart
+++ b/pkg/front_end/lib/src/fasta/fasta_codes_generated.dart
@ -3655,69 +3655,6 @@ const MessageCode messageMissingFunctionParameters = const MessageCode(
        r"""A function declaration needs an explicit list of parameters.""",
    tip: r"""Try adding a parameter list to the function declaration.""");

-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Template<Message Function(String name)>
-    templateMissingImplementationCause =
-    const Template<Message Function(String name)>(
-        messageTemplate: r"""'#name' is defined here.""",
-        withArguments: _withArgumentsMissingImplementationCause);
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Code<Message Function(String name)> codeMissingImplementationCause =
-    const Code<Message Function(String name)>(
-        "MissingImplementationCause", templateMissingImplementationCause,
-        severity: Severity.context);
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-Message _withArgumentsMissingImplementationCause(String name) {
-  return new Message(codeMissingImplementationCause,
-      message: """'$name' is defined here.""", arguments: {'name': name});
-}
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Template<
-    Message Function(
-        String name,
-        String
-            string)> templateMissingImplementationNotAbstract = const Template<
-        Message Function(String name, String string)>(
-    messageTemplate:
-        r"""The non-abstract class '#name' is missing implementations for these members:
-  #string.""",
-    tipTemplate: r"""Try to either
- - provide an implementation,
- - inherit an implementation from a superclass or mixin,
- - mark the class as abstract, or
- - provide a 'noSuchMethod' implementation.
-""",
-    withArguments: _withArgumentsMissingImplementationNotAbstract);
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Code<Message Function(String name, String string)>
-    codeMissingImplementationNotAbstract =
-    const Code<Message Function(String name, String string)>(
-        "MissingImplementationNotAbstract",
-        templateMissingImplementationNotAbstract,
-        analyzerCode: "CONCRETE_CLASS_WITH_ABSTRACT_MEMBER",
-        dart2jsCode: "*fatal*",
-        severity: Severity.errorLegacyWarning);
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-Message _withArgumentsMissingImplementationNotAbstract(
-    String name, String string) {
-  return new Message(codeMissingImplementationNotAbstract,
-      message:
-          """The non-abstract class '$name' is missing implementations for these members:
-  $string.""",
-      tip: """Try to either
- - provide an implementation,
- - inherit an implementation from a superclass or mixin,
- - mark the class as abstract, or
- - provide a 'noSuchMethod' implementation.
-""",
-      arguments: {'name': name, 'string': string});
-}
-
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeMissingInput = messageMissingInput;

--- a/pkg/front_end/lib/src/fasta/kernel/kernel_class_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_class_builder.dart
@ -29,8 +29,6 @@ import 'package:kernel/class_hierarchy.dart' show ClassHierarchy;

 import 'package:kernel/clone.dart' show CloneWithoutBody;

-import 'package:kernel/core_types.dart' show CoreTypes;
-
 import 'package:kernel/type_algebra.dart' show Substitution, getSubstitutionMap;

 import 'package:kernel/type_environment.dart' show TypeEnvironment;
@ -39,15 +37,12 @@ import '../dill/dill_member_builder.dart' show DillMemberBuilder;

 import '../fasta_codes.dart'
    show
-        LocatedMessage,
        Message,
        messagePatchClassOrigin,
        messagePatchClassTypeVariablesMismatch,
        messagePatchDeclarationMismatch,
        messagePatchDeclarationOrigin,
        noLength,
-        templateMissingImplementationCause,
-        templateMissingImplementationNotAbstract,
        templateOverriddenMethodCause,
        templateOverrideFewerNamedArguments,
        templateOverrideFewerPositionalArguments,
@ -293,64 +288,6 @@ abstract class KernelClassBuilder
    });
  }

-  void checkAbstractMembers(CoreTypes coreTypes, ClassHierarchy hierarchy) {
-    if (isAbstract ||
-        hierarchy.getDispatchTarget(cls, noSuchMethodName).enclosingClass !=
-            coreTypes.objectClass) {
-      // Unimplemented members allowed
-      return;
-    }
-
-    List<LocatedMessage> context = null;
-
-    void findMissingImplementations(bool setters) {
-      List<Member> dispatchTargets =
-          hierarchy.getDispatchTargets(cls, setters: setters);
-      int targetIndex = 0;
-      for (Member interfaceMember
-          in hierarchy.getInterfaceMembers(cls, setters: setters)) {
-        if (!interfaceMember.name.isPrivate ||
-            (interfaceMember.enclosingLibrary == cls.enclosingLibrary &&
-                interfaceMember.fileUri ==
-                    interfaceMember.enclosingClass.fileUri)) {
-          while (targetIndex < dispatchTargets.length &&
-              ClassHierarchy.compareMembers(
-                      dispatchTargets[targetIndex], interfaceMember) <
-                  0) {
-            targetIndex++;
-          }
-          if (targetIndex >= dispatchTargets.length ||
-              ClassHierarchy.compareMembers(
-                      dispatchTargets[targetIndex], interfaceMember) >
-                  0) {
-            Name name = interfaceMember.name;
-            String displayName = name.name + (setters ? "=" : "");
-            context ??= <LocatedMessage>[];
-            context.add(templateMissingImplementationCause
-                .withArguments(displayName)
-                .withLocation(interfaceMember.fileUri,
-                    interfaceMember.fileOffset, name.name.length));
-          }
-        }
-      }
-    }
-
-    findMissingImplementations(false);
-    findMissingImplementations(true);
-
-    if (context?.isNotEmpty ?? false) {
-      String memberString =
-          context.map((message) => "'${message.arguments["name"]}'").join(", ");
-      library.addProblem(
-          templateMissingImplementationNotAbstract.withArguments(
-              cls.name, memberString),
-          cls.fileOffset,
-          cls.name.length,
-          cls.fileUri,
-          context: context);
-    }
-  }
-
  // TODO(dmitryas): Find a better place for this routine.
  static bool hasUserDefinedNoSuchMethod(
      Class klass, ClassHierarchy hierarchy) {
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_target.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_target.dart
@ -262,7 +262,6 @@ class KernelTarget extends TargetImplementation {
        loader.performTopLevelInference(myClasses);
      }
      loader.checkOverrides(myClasses);
-      loader.checkAbstractMembers(myClasses);
      loader.addNoSuchMethodForwarders(myClasses);
    } on deprecated_InputError catch (e) {
      ticker.logMs("Got deprecated_InputError");
--- a/pkg/front_end/lib/src/fasta/source/source_loader.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_loader.dart
@ -636,17 +636,6 @@ class SourceLoader<L> extends Loader<L> {
    ticker.logMs("Checked overrides");
  }

-  void checkAbstractMembers(List<SourceClassBuilder> sourceClasses) {
-    if (!target.strongMode) return;
-    assert(hierarchy != null);
-    for (SourceClassBuilder builder in sourceClasses) {
-      if (builder.library.loader == this) {
-        builder.checkAbstractMembers(coreTypes, hierarchy);
-      }
-    }
-    ticker.logMs("Checked abstract members");
-  }
-
  void addNoSuchMethodForwarders(List<SourceClassBuilder> sourceClasses) {
    if (!target.backendTarget.enableNoSuchMethodForwarders) return;

--- a/pkg/front_end/messages.yaml
+++ b/pkg/front_end/messages.yaml
@ -338,7 +338,7 @@ TypedefInClass:
  analyzerCode: TYPEDEF_IN_CLASS
  dart2jsCode: "*fatal*"
  script:
-    - "abstract class C { typedef int F(int x); }"
+    - "class C { typedef int F(int x); }"

 CovariantMember:
  template: "Getters, setters and methods can't be declared to be 'covariant'."
@ -1071,26 +1071,6 @@ AbstractRedirectedClassInstantiation:
  template: "Factory redirects to class '#name', which is abstract and can't be instantiated."
  severity: ERROR_LEGACY_WARNING

-MissingImplementationNotAbstract:
-  template: |
-    The non-abstract class '#name' is missing implementations for these members:
-      #string.
-  tip: |
-    Try to either
-     - provide an implementation,
-     - inherit an implementation from a superclass or mixin,
-     - mark the class as abstract, or
-     - provide a 'noSuchMethod' implementation.
-  severity: ERROR_LEGACY_WARNING
-  analyzerCode: CONCRETE_CLASS_WITH_ABSTRACT_MEMBER
-  dart2jsCode: "*fatal*"
-  script:
-    - "class C {foo();}"
-
-MissingImplementationCause:
-  template: "'#name' is defined here."
-  severity: CONTEXT
-
 ListLiteralTooManyTypeArguments:
  template: "Too many type arguments on List literal."
  severity: ERROR_LEGACY_WARNING
--- a/pkg/front_end/test/fasta/super_mixins_test.dart
+++ b/pkg/front_end/test/fasta/super_mixins_test.dart
@ -60,8 +60,6 @@ class NotMixin extends A with B {
    super.foo(value);
    super.quux();
  }
-
-  void foo(String value) {}
 }

 void main() {
--- a/pkg/front_end/testcases/inference/future_then.dart
+++ b/pkg/front_end/testcases/inference/future_then.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_2.dart
+++ b/pkg/front_end/testcases/inference/future_then_2.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_2.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_2.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_2.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_2.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_2.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_2.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_2.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_2.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_3.dart
+++ b/pkg/front_end/testcases/inference/future_then_3.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_3.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_3.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_3.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_3.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_3.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_3.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_3.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_3.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_4.dart
+++ b/pkg/front_end/testcases/inference/future_then_4.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_4.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_4.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_4.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_4.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_4.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_4.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_4.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_4.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_5.dart
+++ b/pkg/front_end/testcases/inference/future_then_5.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_5.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_5.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_5.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_5.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_5.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_5.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_5.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_5.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_6.dart
+++ b/pkg/front_end/testcases/inference/future_then_6.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_6.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_6.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_6.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_6.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_6.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_6.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_6.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_6.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<dynamic> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional.dart
+++ b/pkg/front_end/testcases/inference/future_then_conditional.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_conditional.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_2.dart
+++ b/pkg/front_end/testcases/inference/future_then_conditional_2.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_conditional_2.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_2.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_2.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_2.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_2.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_2.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_2.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_2.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_3.dart
+++ b/pkg/front_end/testcases/inference/future_then_conditional_3.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_conditional_3.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_3.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_3.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_3.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_3.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_3.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_3.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_3.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_4.dart
+++ b/pkg/front_end/testcases/inference/future_then_conditional_4.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_conditional_4.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_4.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_4.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_4.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_4.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_4.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_4.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_4.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_5.dart
+++ b/pkg/front_end/testcases/inference/future_then_conditional_5.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_conditional_5.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_5.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_5.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_5.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_5.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_5.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_5.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_5.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_6.dart
+++ b/pkg/front_end/testcases/inference/future_then_conditional_6.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_conditional_6.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_6.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_6.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_6.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_6.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_6.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_conditional_6.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_6.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<core::bool> f;
--- a/pkg/front_end/testcases/inference/future_then_ifNull.dart
+++ b/pkg/front_end/testcases/inference/future_then_ifNull.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_ifNull.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_ifNull.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::int> f;
--- a/pkg/front_end/testcases/inference/future_then_ifNull.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_ifNull.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::int> f;
--- a/pkg/front_end/testcases/inference/future_then_ifNull.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_ifNull.dart.outline.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    ;
  constructor value(self::MyFuture::T x) → void
    ;
-  method noSuchMethod(dynamic invocation) → dynamic
-    ;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError}) → self::MyFuture<self::MyFuture::then::S>
    ;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void
  ;
--- a/pkg/front_end/testcases/inference/future_then_ifNull.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_ifNull.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::int> f;
--- a/pkg/front_end/testcases/inference/future_then_ifNull.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_ifNull.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  self::MyFuture<core::int> f;
--- a/pkg/front_end/testcases/inference/future_then_upwards.dart
+++ b/pkg/front_end/testcases/inference/future_then_upwards.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_upwards.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method main() → void {
  dynamic f = self::foo().then((dynamic _) → dynamic => 2.3);
--- a/pkg/front_end/testcases/inference/future_then_upwards.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method main() → void {
  dynamic f = self::foo().then((dynamic _) → dynamic => 2.3);
--- a/pkg/front_end/testcases/inference/future_then_upwards.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method main() → void {
  self::MyFuture<core::double> f = self::foo().{self::MyFuture::then}<core::double>((dynamic _) → core::double => 2.3);
--- a/pkg/front_end/testcases/inference/future_then_upwards.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method main() → void {
  self::MyFuture<core::double> f = self::foo().{self::MyFuture::then}<core::double>((dynamic _) → core::double => 2.3);
--- a/pkg/front_end/testcases/inference/future_then_upwards_2.dart
+++ b/pkg/front_end/testcases/inference/future_then_upwards_2.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_upwards_2.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards_2.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method main() → void {
  dynamic f = self::foo().then((dynamic _) → dynamic => 2.3);
--- a/pkg/front_end/testcases/inference/future_then_upwards_2.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards_2.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method main() → void {
  dynamic f = self::foo().then((dynamic _) → dynamic => 2.3);
--- a/pkg/front_end/testcases/inference/future_then_upwards_2.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards_2.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method main() → void {
  self::MyFuture<core::double> f = self::foo().{self::MyFuture::then}<core::double>((dynamic _) → core::double => 2.3);
--- a/pkg/front_end/testcases/inference/future_then_upwards_2.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards_2.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method main() → void {
  self::MyFuture<core::double> f = self::foo().{self::MyFuture::then}<core::double>((dynamic _) → core::double => 2.3);
--- a/pkg/front_end/testcases/inference/future_then_upwards_3.dart
+++ b/pkg/front_end/testcases/inference/future_then_upwards_3.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(T x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_then_upwards_3.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards_3.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  dynamic f = self::foo().then((dynamic _) → dynamic => 2.3);
--- a/pkg/front_end/testcases/inference/future_then_upwards_3.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards_3.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  dynamic f = self::foo().then((dynamic _) → dynamic => 2.3);
--- a/pkg/front_end/testcases/inference/future_then_upwards_3.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards_3.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<core::double> f = self::foo().{asy::Future::then}<core::double>((dynamic _) → core::double => 2.3);
--- a/pkg/front_end/testcases/inference/future_then_upwards_3.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards_3.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(self::MyFuture::T x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method test() → void {
  asy::Future<core::double> f = self::foo().{asy::Future::then}<core::double>((dynamic _) → core::double => 2.3);
--- a/pkg/front_end/testcases/inference/future_union_async_conditional.dart
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_union_async_conditional.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(dynamic x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method g1(core::bool x) → asy::Future<core::int> async {
  return x ? 42 : asy::Future::value<dynamic>(42);
--- a/pkg/front_end/testcases/inference/future_union_async_conditional.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(dynamic x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method g1(core::bool x) → asy::Future<core::int> /* originally async */ {
  final asy::Completer<core::int> :completer = asy::Completer::sync<core::int>();
--- a/pkg/front_end/testcases/inference/future_union_async_conditional.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(dynamic x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method g1(core::bool x) → asy::Future<core::int> async {
  return (x ?{core::Object} 42 : asy::Future::value<core::int>(42)) as{TypeError} asy::FutureOr<core::int>;
--- a/pkg/front_end/testcases/inference/future_union_async_conditional.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(dynamic x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method g1(core::bool x) → asy::Future<core::int> /* originally async */ {
  final asy::Completer<core::int> :completer = asy::Completer::sync<core::int>();
--- a/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value(x) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(dynamic x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method g1(core::bool x) → asy::Future<core::int> async {
  return x ? 42 : new self::MyFuture::value<dynamic>(42);
--- a/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.direct.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(dynamic x) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method g1(core::bool x) → asy::Future<core::int> /* originally async */ {
  final asy::Completer<core::int> :completer = asy::Completer::sync<core::int>();
--- a/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.strong.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(dynamic x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method g1(core::bool x) → asy::Future<core::int> async {
  return (x ?{core::Object} 42 : new self::MyFuture::value<core::int>(42)) as{TypeError} asy::FutureOr<core::int>;
--- a/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.strong.transformed.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value(dynamic x) → void
    : super core::Object::•() {}
-  method noSuchMethod(core::Invocation invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(core::Invocation invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {generic-covariant-impl generic-covariant-interface () → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static method g1(core::bool x) → asy::Future<core::int> /* originally async */ {
  final asy::Completer<core::int> :completer = asy::Completer::sync<core::int>();
--- a/pkg/front_end/testcases/inference/future_union_downwards.dart
+++ b/pkg/front_end/testcases/inference/future_union_downwards.dart
@ -10,7 +10,7 @@ import 'dart:async';
 class MyFuture<T> implements Future<T> {
  MyFuture() {}
  MyFuture.value([x]) {}
-  dynamic noSuchMethod(/*@topType=Invocation*/ invocation) => null;
+  dynamic noSuchMethod(/*@topType=Invocation*/ invocation);
  MyFuture<S> then<S>(FutureOr<S> f(T x), {Function onError}) => null;
 }

--- a/pkg/front_end/testcases/inference/future_union_downwards.dart.direct.expect
+++ b/pkg/front_end/testcases/inference/future_union_downwards.dart.direct.expect
@ -8,14 +8,9 @@ class MyFuture<T extends core::Object> extends core::Object implements asy::Futu
    : super core::Object::•() {}
  constructor value([dynamic x = null]) → void
    : super core::Object::•() {}
-  method noSuchMethod(dynamic invocation) → dynamic
-    return null;
+  abstract method noSuchMethod(dynamic invocation) → dynamic;
  method then<S extends core::Object>((self::MyFuture::T) → asy::FutureOr<self::MyFuture::then::S> f, {core::Function onError = null}) → self::MyFuture<self::MyFuture::then::S>
    return null;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ catchError(core::Function onError, {(core::Object) → core::bool test = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ whenComplete(() → asy::FutureOr<dynamic> action) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration timeLimit, {() → asy::FutureOr<self::MyFuture::T> onTimeout = null}) → asy::Future<self::MyFuture::T>;
-  abstract no-such-method-forwarder method /* from org-dartlang-testcase-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T>;
 }
 static field self::MyFuture<dynamic> f;
 static field asy::Future<core::int> t1 = self::f.then((dynamic _) → dynamic => asy::Future::value<dynamic>("hi"));
--- a/Show more
+++ b/Show more