add enableAsync to analysis option file flags

pkg/analysis_server/lib/src/status/get_handler.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 analysis_server.src.status.get_handler;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io';
@@ skipping 1234 matching lines @@
           (StringBuffer buffer) {
         buffer.write('<h3>Configuration</h3>');
 
         _writeTwoColumns(buffer, (StringBuffer buffer) {
           AnalysisOptionsImpl options = context.analysisOptions;
           buffer.write('<p><b>Options</b></p>');
           buffer.write('<p>');
           _writeOption(
               buffer, 'Analyze functon bodies', options.analyzeFunctionBodies);
           _writeOption(buffer, 'Cache size', options.cacheSize);
+          _writeOption(buffer, 'Enable async support', options.enableAsync);
           _writeOption(
               buffer, 'Enable generic methods', options.enableGenericMethods);
           _writeOption(buffer, 'Enable strict call checks',
               options.enableStrictCallChecks);
           _writeOption(
               buffer, 'Enable super mixins', options.enableSuperMixins);
           _writeOption(buffer, 'Generate dart2js hints', options.dart2jsHint);
           _writeOption(buffer, 'Generate errors in implicit files',
               options.generateImplicitErrors);
           _writeOption(buffer, 'Generate errors in SDK files',
@@ skipping 1135 matching lines @@
    */
   static String makeLink(
       String path, Map<String, String> params, String innerHtml,
       [bool hasError = false]) {
     Uri uri = new Uri(path: path, queryParameters: params);
     String href = HTML_ESCAPE.convert(uri.toString());
     String classAttribute = hasError ? ' class="error"' : '';
     return '<a href="$href"$classAttribute>$innerHtml</a>';
   }
 }