Fix await parsing.

tests/compiler/dart2js/metadata_test.dart

 // Copyright (c) 2012, 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.
 
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/constants/values.dart'
     show PrimitiveConstantValue;
 import 'package:expect/expect.dart';
 import 'compiler_helper.dart';
 import 'parser_helper.dart';
@@ skipping 136 matching lines @@
       String source,
       Link<MetadataAnnotation> extractMetadata(LibraryElement element)) {
     Uri partUri = new Uri(scheme: 'source', path: 'part.dart');
     String partSource = '@native part of foo;';
 
     Uri libUri = new Uri(scheme: 'source', path: 'lib.dart');
     String libSource = 'library lib;';
 
     Uri uri = new Uri(scheme: 'source', path: 'main.dart');
 
-    Uri async = new Uri(scheme: 'dart', path: 'async');
-
     var compiler = compilerFor(source, uri)
         ..registerSource(partUri, partSource)
-        ..registerSource(libUri, libSource)
-        ..registerSource(async, 'class DeferredLibrary {}');
+        ..registerSource(libUri, libSource);
 
     asyncTest(() => compiler.runCompiler(uri).then((_) {
       compiler.enqueuer.resolution.queueIsClosed = false;
       LibraryElement element = compiler.libraryLoader.lookupLibrary(uri);
       Expect.isNotNull(element, 'Cannot find $uri');
 
       Link<MetadataAnnotation> metadata = extractMetadata(element);
       Expect.equals(1, length(metadata));
 
       PartialMetadataAnnotation annotation = metadata.head;
@@ skipping 38 matching lines @@
   compileAndCheckLibrary(source,
                          (e) => e.compilationUnits.first.partTag.metadata);
 }
 
 void main() {
   testClassMetadata();
   testTopLevelMethodMetadata();
   testTopLevelFieldMetadata();
   testLibraryTags();
 }