Enable dart2js hints test.

pkg/analyzer/test/src/task/dart_test.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.task.dart_test;
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/src/generated/ast.dart';
@@ skipping 1119 matching lines @@
 ''');
     LibraryUnitTarget target = new LibraryUnitTarget(source, source);
     _computeResult(target, HINTS);
     expect(task, new isInstanceOf<GenerateHintsTask>());
     // validate
     _fillErrorListener(HINTS);
     errorListener.assertErrorsWithCodes(<ErrorCode>[HintCode.MISSING_RETURN]);
   }
 
   test_perform_dart2js() {
-    // TODO(scheglov) There is a bug - we need to finish building
-    // TypeProvider hierarchies before validating "expr is CoreType".
-//    Source source = _newSource('/test.dart', '''
-//main(p) {
-//  if (p is double) {
-//    print('double');
-//  }
-//}
-//''');
-//    LibraryUnitTarget target = new LibraryUnitTarget(source, source);
-//    _computeResult(target, HINTS);
-//    expect(task, new isInstanceOf<GenerateHintsTask>());
-//    // validate
-//    _fillErrorListener(HINTS);
-//    errorListener.assertErrorsWithCodes(<ErrorCode>[HintCode.IS_DOUBLE]);
+    Source source = _newSource('/test.dart', '''
+main(p) {
+  if (p is double) {
+    print('double');
+  }
+}
+''');
+    LibraryUnitTarget target = new LibraryUnitTarget(source, source);
+    _computeResult(target, HINTS);
+    expect(task, new isInstanceOf<GenerateHintsTask>());
+    // validate
+    _fillErrorListener(HINTS);
+    errorListener.assertErrorsWithCodes(<ErrorCode>[HintCode.IS_DOUBLE]);
   }
 
   test_perform_deadCode() {
     Source source = _newSource('/test.dart', '''
 main() {
   if (false) {
     print('how?');
   }
 }
 ''');
@@ skipping 558 matching lines @@
     return entryMap.putIfAbsent(target, () => new CacheEntry());
   }
 
   TimestampedData<String> getContents(Source source) => source.contents;
 
   noSuchMethod(Invocation invocation) {
     print('noSuchMethod: ${invocation.memberName}');
     return super.noSuchMethod(invocation);
   }
 }