Add constructors to all the event classes.

client/html/src/HashChangeEvent.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.
+interface HashChangeEvent extends Event factory HashChangeEventWrappingImplementation {
 
-interface HashChangeEvent extends Event {
+  HashChangeEvent(String type, String oldURL, String newURL, [bool canBubble,
+      bool cancelable]);
 
   String get newURL();
 
   String get oldURL();
-
-  void initHashChangeEvent(String type, bool canBubble, bool cancelable, String oldURL, String newURL);
 }