Use userAgent instead of webkitStartDart

client/dart.js

 // 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.
 
 var warning = [
   'WARNING: This page is using a deprecated dart.js file. ',
   'Please update this page as described here: ',
   'http://news.dartlang.org/2013/01/big-breaking-change-dartjs-bootstrap-file-moving-to-pub.html'
 ].join('');
 console.error(warning);
 
 // Bootstrap support for Dart scripts on the page as this script.
-if (navigator.webkitStartDart) {
-  if (!navigator.webkitStartDart()) {
-    document.body.innerHTML = 'This build has expired.  Please download a new Dartium at http://www.dartlang.org/dartium/index.html';
-  }
-} else {
+if (navigator.userAgent.indexOf('(Dart)') === -1) {

[ricow1, 2013/10/30 06:35:25]

indexOf should always return a number, so strictly speaking you don't need ===
here.
Additionally, isn't the innerHTML setting still valid if the build is expired?

   // TODO:
   // - Support in-browser compilation.
   // - Handle inline Dart scripts.
   window.addEventListener("DOMContentLoaded", function (e) {
     // Fall back to compiled JS. Run through all the scripts and
     // replace them if they have a type that indicate that they source
     // in Dart code.
     //
     //   <script type="application/dart" src="..."></script>
     //
@@ skipping 176 matching lines @@
   };
 
   ReceivePortSync.prototype.toSendPort = function() {
     return new LocalSendPortSync(this);
   };
 
   ReceivePortSync.prototype.close = function() {
     delete ReceivePortSync.map[this.id];
   };
 
-  if (navigator.webkitStartDart) {
+  if (navigator.userAgent.indexOf('(Dart)') !== -1) {
     window.addEventListener('js-sync-message', function(event) {
       var data = JSON.parse(getPortSyncEventData(event));
       var deserialized = deserialize(data.message);
       var result = ReceivePortSync.map[data.id].callback(deserialized);
       // TODO(vsm): Handle and propagate exceptions.
       dispatchEvent('js-result', serialize(result));
     }, false);
   }
 
   function LocalSendPortSync(receivePort) {
@@ skipping 35 matching lines @@
     var result = null;
     var listener = function (e) {
       result = JSON.parse(getPortSyncEventData(e));
     };
     window.addEventListener(source, listener, false);
     dispatchEvent(target, [source, serialized]);
     window.removeEventListener(source, listener, false);
     return deserialize(result);
   }
 })();