Start marking @_fastaProblem, fix for unresolved mixin, fix for type parameter context.

pkg/analyzer/test/src/summary/resynthesize_common.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
 library test.src.serialization.elements_test;
 
 import 'dart:async';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_resolution_map.dart';
@@ skipping 2095 matching lines @@
 }
 class B<B1> {
 }
 class C<C1> {
 }
 ''');
   }
 
   test_class_mixins_unresolved() async {
     var library = await checkLibrary(
-        'class C extends Object with X, Y, Z; class X {} class Z {}',
+        'class C extends Object with X, Y, Z {} class X {} class Z {}',
         allowErrors: true);
     checkElementText(library, r'''
 class C extends Object with X, Z {
   synthetic C();
 }
 class X {
 }
 class Z {
 }
 ''');
@@ skipping 7729 matching lines @@
       fail('Unexpectedly tried to get unlinked summary for $uri');
     }
     return serializedUnit;
   }
 
   @override
   bool hasLibrarySummary(String uri) {
     return true;
   }
 }