Add constructors to all the event classes.

client/html/src/MouseEvent.dart

Index: client/html/src/MouseEvent.dart
diff --git a/client/html/generated/src/interface/MouseEvent.dart b/client/html/src/MouseEvent.dart
similarity index 63%
rename from client/html/generated/src/interface/MouseEvent.dart
rename to client/html/src/MouseEvent.dart
index 854290225163e05fefa58c398b2c6a93f358d619..ceb1a6ec3019085290c9cf3e2af87a0767d5ff4d 100644
--- a/client/html/generated/src/interface/MouseEvent.dart
+++ b/client/html/src/MouseEvent.dart
@@ -2,9 +2,12 @@
 // 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.
+interface MouseEvent extends UIEvent factory MouseEventWrappingImplementation {
 
-interface MouseEvent extends UIEvent {
+  MouseEvent(String type, Window view, int detail, int screenX, int screenY,
+      int clientX, int clientY, int button, [bool canBubble, bool cancelable,
+      bool ctrlKey, bool altKey, bool shiftKey, bool metaKey,
+      EventTarget relatedTarget]);
 
   bool get altKey();
 
@@ -37,6 +40,4 @@ interface MouseEvent extends UIEvent {
   int get x();
 
   int get y();
-
-  void initMouseEvent(String type, bool canBubble, bool cancelable, Window view, int detail, int screenX, int screenY, int clientX, int clientY, bool ctrlKey, bool altKey, bool shiftKey, bool metaKey, int button, EventTarget relatedTarget);
 }