De-flaking custom element test.

tests/html/custom_elements_test.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 custom_elements_test;
 import 'dart:async';
 import 'dart:html';
 import 'package:unittest/html_individual_config.dart';
 import 'package:unittest/unittest.dart';
 
@@ skipping 20 matching lines @@
 
 int customCreatedCount = 0;
 
 int nextTagId = 0;
 String get nextTag => 'x-type${nextTagId++}';
 
 class NotAnElement {}
 
 loadPolyfills() {
   if (!document.supportsRegister) {
+    // Cache blocker is a workaround for:
+    // https://code.google.com/p/dart/issues/detail?id=11834
+    var cacheBlocker = new DateTime.now().millisecondsSinceEpoch;
     return HttpRequest.getString('/root_dart/pkg/custom_element/lib/'
-      'custom-elements.debug.js').then((code) {
+      'custom-elements.debug.js?cacheBlock=$cacheBlocker').then((code) {
       document.head.children.add(new ScriptElement()..text = code);
     });
   }
 }
 
 main() {
   useHtmlIndividualConfiguration();
 
   setUp(loadPolyfills);
 
@@ skipping 127 matching lines @@
     test('can invoke mixin methods', () {
       var tag = nextTag;
       document.register(tag, CustomType);
 
       var element = new Element.tag(tag);
       element.invokeMixinMethod();
       expect(element.mixinMethodCalled, isTrue);
     });
   });
 }