Add a temporary analyzer error to work around #28515

pkg/analyzer/test/src/context/context_test.dart

 // Copyright (c) 2014, 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 analyzer.test.src.context.context_test;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 2516 matching lines @@
       sdkResolver,
       resourceResolver,
       new PackageMapUriResolver(resourceProvider, {
         'crypto': [resourceProvider.getFolder('/pkgs/crypto-2/lib')]
       })
     ]);
     _analyzeAll_assertFinished();
     _assertNoExceptions();
   }
 
+  @failingTest // TODO(paulberry): Remove when dartbug.com/28515 is fixed.

[Brian Wilkerson, 2017/01/27 19:37:05]

"Remove when" --> "Remove the annotation when"

[Paul Berry, 2017/01/29 15:28:57]

Done.

   void test_resolveCompilationUnit_existingElementModel() {
     prepareAnalysisContext(new AnalysisOptionsImpl()..strongMode = true);
     Source source = addSource(
         '/test.dart',
         r'''
 library test;
 
 String topLevelVariable;
 int get topLevelGetter => 0;
 void set topLevelSetter(int value) {}
@@ skipping 2892 matching lines @@
    * Initialize the visitor.
    */
   _ElementGatherer();
 
   @override
   void visitElement(Element element) {
     elements[element] = element;
     super.visitElement(element);
   }
 }