Add constructors to all the event classes.

client/html/src/WheelEvent.dart

Index: client/html/src/WheelEvent.dart
diff --git a/client/html/generated/src/interface/WheelEvent.dart b/client/html/src/WheelEvent.dart
similarity index 68%
rename from client/html/generated/src/interface/WheelEvent.dart
rename to client/html/src/WheelEvent.dart
index 6eebf24685fbe7231e3938abb847e89d7ca52fdb..f6c54c05447d5c966cf55aacd2292b577e7d0dff 100644
--- a/client/html/generated/src/interface/WheelEvent.dart
+++ b/client/html/src/WheelEvent.dart
@@ -2,9 +2,11 @@
 // 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 WheelEvent extends UIEvent factory WheelEventWrappingImplementation {
 
-interface WheelEvent extends UIEvent {
+  WheelEvent(int deltaX, int deltaY, Window view, int screenX, int screenY,
+      int clientX, int clientY, [bool ctrlKey, bool altKey, bool shiftKey,
+      bool metaKey]);
 
   bool get altKey();
 
@@ -35,6 +37,4 @@ interface WheelEvent extends UIEvent {
   int get x();
 
   int get y();
-
-  void initWheelEvent(int wheelDeltaX, int wheelDeltaY, Window view, int screenX, int screenY, int clientX, int clientY, bool ctrlKey, bool altKey, bool shiftKey, bool metaKey);
 }