Add constructors to all the event classes.

client/html/src/WheelEventWrappingImplementation.dart

Index: client/html/src/WheelEventWrappingImplementation.dart
diff --git a/client/html/generated/src/wrapping/_WheelEventWrappingImplementation.dart b/client/html/src/WheelEventWrappingImplementation.dart
similarity index 69%
rename from client/html/generated/src/wrapping/_WheelEventWrappingImplementation.dart
rename to client/html/src/WheelEventWrappingImplementation.dart
index d597cbeacc7c4a0486c69d027ae5dfffe7525703..1e872a878f34e556740ec0f8d7a34ed9b808f7e0 100644
--- a/client/html/generated/src/wrapping/_WheelEventWrappingImplementation.dart
+++ b/client/html/src/WheelEventWrappingImplementation.dart
@@ -2,11 +2,18 @@
 // 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 WheelEventWrappingImplementation extends UIEventWrappingImplementation implements WheelEvent {
   WheelEventWrappingImplementation._wrap(ptr) : super._wrap(ptr) {}
 
+  factory WheelEventWrappingImplementation(int deltaX, int deltaY, Window view,
+      int screenX, int screenY, int clientX, int clientY, [bool ctrlKey = false,
+      bool altKey = false, bool shiftKey = false, bool metaKey = false]) {
+    var e = dom.document.createEvent("WheelEvent");
+    e.initWheelEvent(deltaX, deltaY, LevelDom.unwrap(view), screenX, screenY,
+        clientX, clientY, ctrlKey, altKey, shiftKey, metaKey);
+    return LevelDom.wrapWheelEvent(e);
+  }
+
   bool get altKey() { return _ptr.altKey; }
 
   int get clientX() { return _ptr.clientX; }
@@ -36,9 +43,4 @@ class WheelEventWrappingImplementation extends UIEventWrappingImplementation imp
   int get x() { return _ptr.x; }
 
   int get y() { return _ptr.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) {
-    _ptr.initWheelEvent(wheelDeltaX, wheelDeltaY, LevelDom.unwrap(view), screenX, screenY, clientX, clientY, ctrlKey, altKey, shiftKey, metaKey);
-    return;
-  }
 }