Make Try Dart tests run on Firefox.

dart/site/try/src/ui.dart

 // Copyright (c) 2013, 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 trydart.ui;
 
 import 'dart:html';
 
 import 'dart:async' show
     Future,
@@ skipping 159 matching lines @@
         var save = new AnchorElement(href: blobUrl);
         save.target = '_blank';
         save.download = 'untitled.dart';
         save.dispatchEvent(new Event.eventType('Event', 'click'));
       })
       ..style.position = 'absolute'
       ..style.right = '0px'
       ..appendText('Save');
 
   cacheStatusElement = document.getElementById('appcache-status');
-  updateCacheStatus();
+  updateCacheStatus(null);
 
   var section = document.querySelector('article[class="homepage"]>section');
 
   DivElement tryColumn = document.getElementById('try-dart-column');
   DivElement runColumn = document.getElementById('run-dart-column');
 
   tryColumn.append(inputWrapper);
   outputFrame.style.display = 'none';
   runColumn.append(outputFrame);
   runColumn.append(outputWrapper);
@@ skipping 291 matching lines @@
     window.localStorage['compilationPaused'] = '$compilationPaused';
     window.localStorage['codeFont'] = '$codeFont';
 
     dialog.style.height = '0px';
   }
   form.onSubmit.listen(onSubmit);
 
   var doneButton = document.getElementById('settings-done');
   doneButton.onClick.listen(onSubmit);
 }