Adding Element.created constructor

tools/dom/src/native_DOMImplementation.dart

 // 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.
 
 part of html;
 
 class _ConsoleVariables {
   Map<String, Object> _data = new Map<String, Object>();
 
   /**
@@ skipping 271 matching lines @@
     return libName.startsWith('dart:');
   }
 
   static void register(Document document, String tag, Type type,
       String extendsTagName) {
     // TODO(vsm): Move these checks into native code.
     ClassMirror cls = reflectClass(type);
     if (_isBuiltinType(cls)) {
       throw new UnsupportedError("Invalid custom element from $libName.");
     }
+    var className = MirrorSystem.getName(cls.simpleName);
+    if (!cls.constructors.containsKey(new Symbol('$className.created'))) {
+      throw new UnsupportedError('Class is missing constructor $className.created');
+    }
     _register(document, tag, type, extendsTagName);
   }
 
   static void _register(Document document, String tag, Type customType,
       String extendsTagName) native "Utils_register";
 
   static Element createElement(Document document, String tagName) native "Utils_createElement";
+
+  static void initializeCustomElement(HtmlElement element) native "Utils_initializeCustomElement";
 }
 
 class _NPObject extends NativeFieldWrapperClass1 {
   _NPObject.internal();
   static _NPObject retrieve(String key) native "NPObject_retrieve";
   property(String propertyName) native "NPObject_property";
   invoke(String methodName, [List args = null]) native "NPObject_invoke";
 }
 
 class _DOMWindowCrossFrame extends NativeFieldWrapperClass1 implements
@@ skipping 201 matching lines @@
   _send(msg) {
     _sendToHelperIsolate(msg, _sendPort);
   }
 
   bool get isActive => _isActive;
 }
 
 get _pureIsolateTimerFactoryClosure =>
     ((int milliSeconds, void callback(Timer time), bool repeating) =>
         new _PureIsolateTimer(milliSeconds, callback, repeating));
+
+void _initializeCustomElement(Element e) {
+  _Utils.initializeCustomElement(e);
+}