Add constructors to all the event classes.

client/html/src/HashChangeEventWrappingImplementation.dart

 // Copyright (c) 2011, 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.
 
-// WARNING: Do not edit - generated code.
-
 class HashChangeEventWrappingImplementation extends EventWrappingImplementation implements HashChangeEvent {
   HashChangeEventWrappingImplementation._wrap(ptr) : super._wrap(ptr) {}
 
+  factory HashChangeEventWrappingImplementation(String type, String oldURL,
+      String newURL, [bool canBubble = false, bool cancelable = false]) {
+    var e = dom.document.createEvent("HashChangeEvent");
+    e.initHashChangeEvent(type, canBubble, cancelable, oldURL, newURL);
+    return LevelDom.wrapHashChangeEvent(e);
+  }
+
   String get newURL() { return _ptr.newURL; }
 
   String get oldURL() { return _ptr.oldURL; }
-
-  void initHashChangeEvent(String type, bool canBubble, bool cancelable, String oldURL, String newURL) {
-    _ptr.initHashChangeEvent(type, canBubble, cancelable, oldURL, newURL);
-    return;
-  }
 }