Quick Fix for adding 'async' to fix invalid 'await'.

pkg/analysis_server/lib/src/services/correction/fix.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 services.correction.fix;
 
 import 'package:analysis_server/src/protocol.dart' show SourceChange;
 import 'package:analysis_server/src/services/correction/fix_internal.dart';
 import 'package:analysis_server/src/services/search/search_engine.dart';
 import 'package:analyzer/src/generated/ast.dart';
@@ skipping 29 matching lines @@
   String toString() {
     return '[kind=$kind, change=$change]';
   }
 }
 
 
 /**
  * An enumeration of possible quick fix kinds.
  */
 class FixKind {
+  static const ADD_ASYNC =
+      const FixKind('ADD_ASYNC', 50, "Add 'async' modifier");
   static const ADD_PACKAGE_DEPENDENCY =
       const FixKind('ADD_PACKAGE_DEPENDENCY', 50, "Add dependency on package '{0}'");
   static const ADD_SUPER_CONSTRUCTOR_INVOCATION = const FixKind(
       'ADD_SUPER_CONSTRUCTOR_INVOCATION',
       50,
       "Add super constructor {0} invocation");
   static const CHANGE_TO = const FixKind('CHANGE_TO', 49, "Change to '{0}'");
   static const CHANGE_TO_STATIC_ACCESS = const FixKind(
       'CHANGE_TO_STATIC_ACCESS',
       50,
@@ skipping 70 matching lines @@
 
   final name;
   final int relevance;
   final String message;
 
   const FixKind(this.name, this.relevance, this.message);
 
   @override
   String toString() => name;
 }