Add constructors to all the event classes.

client/html/src/PopStateEventWrappingImplementation.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 PopStateEventWrappingImplementation extends EventWrappingImplementation implements PopStateEvent {
+  PopStateEventWrappingImplementation._wrap(ptr) : super._wrap(ptr);
 
-class PopStateEventWrappingImplementation extends EventWrappingImplementation implements PopStateEvent {
-  PopStateEventWrappingImplementation._wrap(ptr) : super._wrap(ptr) {}
+  factory PopStateEventWrappingImplementation(String type, Object state,
+      [bool canBubble = true, bool cancelable = true]) {
+    final e = dom.document.createEvent("PopStateEvent");
+    e.initPopStateEvent(type, canBubble, cancelable, state);
+    return LevelDom.wrapPopStateEvent(e);
+  }
 
-  String get state() { return _ptr.state; }
-
-  void initPopStateEvent(String typeArg, bool canBubbleArg, bool cancelableArg, Object stateArg) {
-    _ptr.initPopStateEvent(typeArg, canBubbleArg, cancelableArg, LevelDom.unwrapMaybePrimitive(stateArg));
-    return;
-  }
+  String get state() => _ptr.state;
 }