Add constructors to all the event classes.

client/html/generated/src/wrapping/_EventWrappingImplementation.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 EventWrappingImplementation extends DOMWrapperBase implements Event {
-  EventWrappingImplementation._wrap(ptr) : super._wrap(ptr) {}
-
-  bool get bubbles() { return _ptr.bubbles; }
-
-  bool get cancelBubble() { return _ptr.cancelBubble; }
-
-  void set cancelBubble(bool value) { _ptr.cancelBubble = value; }
-
-  bool get cancelable() { return _ptr.cancelable; }
-
-  EventTarget get currentTarget() { return LevelDom.wrapEventTarget(_ptr.currentTarget); }
-
-  bool get defaultPrevented() { return _ptr.defaultPrevented; }
-
-  int get eventPhase() { return _ptr.eventPhase; }
-
-  bool get returnValue() { return _ptr.returnValue; }
-
-  void set returnValue(bool value) { _ptr.returnValue = value; }
-
-  EventTarget get srcElement() { return LevelDom.wrapEventTarget(_ptr.srcElement); }
-
-  EventTarget get target() { return LevelDom.wrapEventTarget(_ptr.target); }
-
-  int get timeStamp() { return _ptr.timeStamp; }
-
-  String get type() { return _ptr.type; }
-
-  void initEvent(String eventTypeArg, bool canBubbleArg, bool cancelableArg) {
-    _ptr.initEvent(eventTypeArg, canBubbleArg, cancelableArg);
-    return;
-  }
-
-  void preventDefault() {
-    _ptr.preventDefault();
-    return;
-  }
-
-  void stopImmediatePropagation() {
-    _ptr.stopImmediatePropagation();
-    return;
-  }
-
-  void stopPropagation() {
-    _ptr.stopPropagation();
-    return;
-  }
-}