Make WheelEvent.delta{X,Y} return num, not int.

lib/html/dart2js/html_dart2js.dart

Index: lib/html/dart2js/html_dart2js.dart
diff --git a/lib/html/dart2js/html_dart2js.dart b/lib/html/dart2js/html_dart2js.dart
index 68bcf429f283cfcbb3f82e6c660e182eecca0986..49176d8480285c1b323f459f2101c3ce465536bf 100644
--- a/lib/html/dart2js/html_dart2js.dart
+++ b/lib/html/dart2js/html_dart2js.dart
@@ -36918,18 +36918,18 @@ abstract class WheelEvent implements MouseEvent {
   /** @domName WheelEvent.webkitDirectionInvertedFromDevice */
   abstract bool get webkitDirectionInvertedFromDevice;
 
-  /** @domName WheelEvent.deltaX */
-  abstract int get deltaX;
-
-  /** @domName WheelEvent.deltaY */
-  abstract int get deltaY;
-
   /** @domName WheelEvent.initWebKitWheelEvent */
   void initWebKitWheelEvent(int wheelDeltaX, int wheelDeltaY, LocalWindow view, int screenX, int screenY, int clientX, int clientY, bool ctrlKey, bool altKey, bool shiftKey, bool metaKey);
 
 
+  /** @domName WheelEvent.deltaX */
+  abstract num get deltaX;
+
+  /** @domName WheelEvent.deltaY */
+  abstract num get deltaY;
+
   /** @domName WheelEvent.deltaMode */
-  int get deltaMode;
+  abstract int get deltaMode;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a