Add constructors to all the event classes.

client/html/generated/src/wrapping/_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) {}
-
-  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;
-  }
-}