Add constructors to all the event classes.

client/html/generated/src/wrapping/_UIEventWrappingImplementation.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 UIEventWrappingImplementation extends EventWrappingImplementation implements UIEvent {
-  UIEventWrappingImplementation._wrap(ptr) : super._wrap(ptr) {}
-
-  int get charCode() { return _ptr.charCode; }
-
-  int get detail() { return _ptr.detail; }
-
-  int get keyCode() { return _ptr.keyCode; }
-
-  int get layerX() { return _ptr.layerX; }
-
-  int get layerY() { return _ptr.layerY; }
-
-  int get pageX() { return _ptr.pageX; }
-
-  int get pageY() { return _ptr.pageY; }
-
-  Window get view() { return LevelDom.wrapWindow(_ptr.view); }
-
-  int get which() { return _ptr.which; }
-
-  void initUIEvent(String type, bool canBubble, bool cancelable, Window view, int detail) {
-    _ptr.initUIEvent(type, canBubble, cancelable, LevelDom.unwrap(view), detail);
-    return;
-  }
-}