[flip-modifiers] opt out from class modifiers some failing front end language tests

Change-Id: I7c6473b2c1dd401355b18b55c8d3ce9b0cfaf257
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/286541
Commit-Queue: Jake Macdonald <jakemac@google.com>
Reviewed-by: Bob Nystrom <rnystrom@google.com>
Commit-Queue: Bob Nystrom <rnystrom@google.com>
Auto-Submit: Jake Macdonald <jakemac@google.com>

tests/language/deferred/inheritance_constraints_lib.dart

@@ -2,6 +2,11 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// TODO(https://github.com/dart-lang/sdk/issues/51557): Decide if the mixins
+// being applied in this test should be "mixin", "mixin class" or the test
+// should be left at 2.19.
+// @dart=2.19
+
 class Foo {}
 
 class Foo2 {}

tests/language/deferred/inheritance_constraints_test.dart

@@ -2,6 +2,11 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// TODO(https://github.com/dart-lang/sdk/issues/51557): Decide if the mixins
+// being applied in this test should be "mixin", "mixin class" or the test
+// should be left at 2.19.
+// @dart=2.19
+
 import "package:expect/expect.dart";
 import "inheritance_constraints_lib.dart" deferred as lib;
 

tests/language/enum/enhanced_enums_subtype_error_test.dart

@@ -2,6 +2,11 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// TODO(https://github.com/dart-lang/sdk/issues/51557): Decide if the mixins
+// being applied in this test should be "mixin", "mixin class" or the test
+// should be left at 2.19.
+// @dart=2.19
+
 // Test errors required by new enhanced enum syntax.
 
 // Classes which implement `Enum`, but are not `enum` declarations,

tests/language/mixin/illegal_object_test.dart

@@ -2,6 +2,11 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// TODO(https://github.com/dart-lang/sdk/issues/51557): Decide if the mixins
+// being applied in this test should be "mixin", "mixin class" or the test
+// should be left at 2.19.
+// @dart=2.19
+
 // Object has a non-trivial constructor and hence cannot be used as mixin.
 
 class S {}

tests/language/nonfunction_type_aliases/usage_object_error_test.dart

@@ -2,6 +2,11 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// TODO(https://github.com/dart-lang/sdk/issues/51557): Decide if the mixins
+// being applied in this test should be "mixin", "mixin class" or the test
+// should be left at 2.19.
+// @dart=2.19
+
 
 // Introduce an aliased type.
 

tests/language/null/inherit_static_errors_test.dart

@@ -2,6 +2,11 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// TODO(https://github.com/dart-lang/sdk/issues/51557): Decide if the mixins
+// being applied in this test should be "mixin", "mixin class" or the test
+// should be left at 2.19.
+// @dart=2.19
+
 class BadExtends extends Null {}
 //                       ^^^^
 // [analyzer] COMPILE_TIME_ERROR.SUBTYPE_OF_DISALLOWED_TYPE

tests/lib/typed_data/restricted_types_error_test.dart

@@ -2,6 +2,11 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// TODO(https://github.com/dart-lang/sdk/issues/51557): Decide if the mixins
+// being applied in this test should be "mixin", "mixin class" or the test
+// should be left at 2.19.
+// @dart=2.19
+
 import 'dart:typed_data';
 
 abstract class CEByteBuffer extends ByteBuffer {}