Fix analyzer/FE integration of assignment with synthetic LHS, inside class method.

Error recovery generates a slightly different kernel representation
for "= x" inside a class method vs. outside a class method.  Inside a
class method, the synthetic LHS is a property access; outside a class
method it is a variable access.  The "outside a class method" case was
addressed in 55aa031404f36d181daf5f5b27424da431ee2e3e; this CL
addresses the "inside a class method" case.

Fixes 1 language test with [ $compiler == dart2analyzer && $fasta ].

Change-Id: Ib9429cac13b775a7d0b40a13468117c442611531
Reviewed-on: https://dart-review.googlesource.com/71223
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>

pkg/analyzer/lib/src/fasta/resolution_storer.dart

@@ -573,12 +573,14 @@ class ResolutionStorer
   void propertyAssign(
       ExpressionJudgment judgment,
       int location,
+      bool isSyntheticLhs,
       DartType receiverType,
       Node writeMember,
       DartType writeContext,
       Node combiner,
       DartType inferredType) {
     _store(location,
+        isSynthetic: isSyntheticLhs,
         isWriteReference: true,
         reference: writeMember,
         writeContext: writeContext,

pkg/analyzer/test/src/dart/analysis/driver_resolution_test.dart

@@ -969,6 +969,21 @@ void f(int x) {
     assertElement(xRef, findElement.parameter('x'));
   }
 
+  test_assign_with_synthetic_lhs_in_method() async {
+    addTestFile('''
+class C {
+  void f(int x) {
+    = x;
+  }
+}
+''');
+    await resolveTestFile();
+
+    var xRef = findNode.simple('x;');
+    assertType(xRef, 'int');
+    assertElement(xRef, findElement.parameter('x'));
+  }
+
   test_assignment_to_final_parameter() async {
     addTestFile('''
 f(final int x) {

pkg/front_end/lib/src/fasta/kernel/kernel_expression_generator.dart

@@ -501,7 +501,8 @@ class KernelThisPropertyAccessGenerator extends KernelGenerator
 
   @override
   ComplexAssignmentJudgment startComplexAssignment(Expression rhs) =>
-      new PropertyAssignmentJudgment(null, rhs);
+      new PropertyAssignmentJudgment(null, rhs,
+          isSyntheticLhs: token.isSynthetic);
 
   @override
   void printOn(StringSink sink) {

pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart

@@ -2234,10 +2234,11 @@ class PropertyAssignmentJudgment extends ComplexAssignmentJudgmentWithReceiver {
   /// If this assignment uses null-aware access (`?.`), the conditional
   /// expression that guards the access; otherwise `null`.
   ConditionalExpression nullAwareGuard;
+  final bool isSyntheticLhs;
 
   PropertyAssignmentJudgment(
       ExpressionJudgment receiver, ExpressionJudgment rhs,
-      {bool isSuper: false})
+      {bool isSuper: false, this.isSyntheticLhs: false})
       : super(receiver, rhs, isSuper);
 
   @override
@@ -2287,6 +2288,7 @@ class PropertyAssignmentJudgment extends ComplexAssignmentJudgmentWithReceiver {
     inferrer.listener.propertyAssign(
         this,
         write.fileOffset,
+        isSyntheticLhs,
         receiverType,
         inferrer.getRealTarget(writeMember),
         writeContext,

pkg/front_end/lib/src/fasta/type_inference/type_inference_listener.dart

@@ -643,6 +643,7 @@ abstract class TypeInferenceListener<Location, Reference, PrefixInfo> {
   void propertyAssign(
       ExpressionJudgment judgment,
       Location location,
+      bool isSyntheticLhs,
       DartType receiverType,
       Reference writeMember,
       DartType writeContext,
@@ -1060,8 +1061,15 @@ class KernelTypeInferenceListener
       NullLiteralTokens tokens, bool isSynthetic, DartType inferredType) {}
 
   @override
-  void propertyAssign(ExpressionJudgment judgment, location, receiverType,
-      writeMember, DartType writeContext, combiner, DartType inferredType) {}
+  void propertyAssign(
+      ExpressionJudgment judgment,
+      location,
+      bool isSyntheticLhs,
+      receiverType,
+      writeMember,
+      DartType writeContext,
+      combiner,
+      DartType inferredType) {}
 
   @override
   void propertyGet(ExpressionJudgment judgment, location,

tests/language_2/language_2_analyzer.status

@@ -31,7 +31,6 @@ arg_param_trailing_comma_test/138: Crash # Error recovery in method body (synthe
 arg_param_trailing_comma_test/147: Crash # Error recovery in method body (synthetic argument)
 arg_param_trailing_comma_test/156: Crash # Error recovery in method body (synthetic argument)
 arg_param_trailing_comma_test/165: Crash # Error recovery in method body (synthetic argument)
-arg_param_trailing_comma_test/166: Crash # Error recovery in method body (invalid assignment)
 arg_param_trailing_comma_test/24: Crash # Issue #34043 - Error recovery in outline (extraneous comma before formal parameter)
 arg_param_trailing_comma_test/25: Crash # Issue #34043 - Error recovery in outline (extraneous comma before formal parameter)
 arg_param_trailing_comma_test/26: Crash # Issue #34043 - Error recovery in outline (extraneous comma before formal parameter)