Adding Element.created constructor

tests/html/custom/constructor_calls_created_synchronously_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 constructor_calls_created_synchronously_test;
 import 'package:unittest/unittest.dart';
 import 'package:unittest/html_config.dart';
 import 'dart:html';
 import '../utils.dart';
+import 'dart:mirrors';
 
 class A extends HtmlElement {
   static final tag = 'x-a';
   factory A() => new Element.tag(tag);
+  A.created() : super.created();
 
   static int ncallbacks = 0;
 
-  void created() {
+  void createdCallback() {
     ncallbacks++;
   }
 }
 
 main() {
   useHtmlConfiguration();
 
   // Adapted from Blink's
   // fast/dom/custom/constructor-calls-created-synchronously test.
 
   setUp(loadPolyfills);
 
   test('createdCallback', () {
     document.register(A.tag, A);
     var x = new A();
     expect(A.ncallbacks, 1);
   });
 }