Add constructors to all the event classes.

client/html/generated/src/wrapping/_MessageEventWrappingImplementation.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 MessageEventWrappingImplementation extends EventWrappingImplementation implements MessageEvent {
-  MessageEventWrappingImplementation._wrap(ptr) : super._wrap(ptr) {}
-
-  String get data() { return _ptr.data; }
-
-  String get lastEventId() { return _ptr.lastEventId; }
-
-  MessagePort get messagePort() { return LevelDom.wrapMessagePort(_ptr.messagePort); }
-
-  String get origin() { return _ptr.origin; }
-
-  Window get source() { return LevelDom.wrapWindow(_ptr.source); }
-
-  void initMessageEvent(String typeArg, bool canBubbleArg, bool cancelableArg, String dataArg, String originArg, String lastEventIdArg, Window sourceArg, MessagePort messagePort) {
-    _ptr.initMessageEvent(typeArg, canBubbleArg, cancelableArg, dataArg, originArg, lastEventIdArg, LevelDom.unwrap(sourceArg), LevelDom.unwrap(messagePort));
-    return;
-  }
-}