add parser parseAsync flag

pkg/analyzer/lib/src/context/context.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 analyzer.src.context.context;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/dart/element/element.dart';
@@ skipping 235 matching lines @@
         (this._options.lint && !options.lint) ||
         this._options.preserveComments != options.preserveComments ||
         this._options.strongMode != options.strongMode ||
         this._options.enableAssertMessage != options.enableAssertMessage ||
         ((options is AnalysisOptionsImpl)
             ? this._options.strongModeHints != options.strongModeHints
             : false) ||
         this._options.enableStrictCallChecks !=
             options.enableStrictCallChecks ||
         this._options.enableGenericMethods != options.enableGenericMethods ||
+        this._options.enableAsync != options.enableAsync ||
         this._options.enableSuperMixins != options.enableSuperMixins;
     int cacheSize = options.cacheSize;
     if (this._options.cacheSize != cacheSize) {
       this._options.cacheSize = cacheSize;
     }
     this._options.analyzeFunctionBodiesPredicate =
         options.analyzeFunctionBodiesPredicate;
     this._options.generateImplicitErrors = options.generateImplicitErrors;
     this._options.generateSdkErrors = options.generateSdkErrors;
     this._options.dart2jsHint = options.dart2jsHint;
     this._options.enableGenericMethods = options.enableGenericMethods;
     this._options.enableAssertMessage = options.enableAssertMessage;
     this._options.enableStrictCallChecks = options.enableStrictCallChecks;
+    this._options.enableAsync = options.enableAsync;
     this._options.enableSuperMixins = options.enableSuperMixins;
     this._options.hint = options.hint;
     this._options.incremental = options.incremental;
     this._options.incrementalApi = options.incrementalApi;
     this._options.incrementalValidation = options.incrementalValidation;
     this._options.lint = options.lint;
     this._options.preserveComments = options.preserveComments;
     this._options.strongMode = options.strongMode;
     if (options is AnalysisOptionsImpl) {
       this._options.strongModeHints = options.strongModeHints;
@@ skipping 1750 matching lines @@
     }
     DartSdk sdk = factory.dartSdk;
     if (sdk == null) {
       throw new IllegalArgumentException(
           "The source factory for an SDK analysis context must have a DartUriResolver");
     }
     return new AnalysisCache(
         <CachePartition>[AnalysisEngine.instance.partitionManager.forSdk(sdk)]);
   }
 }