Fixing dartc error about not using ~/ operator and FF test error.

tools/dom/templates/html/impl/impl_WheelEvent.darttemplate

 // 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
 // BSD-style license that can be found in the LICENSE file.
 
 part of html;
 $ANNOTATIONS
 class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
 
   factory WheelEvent(String type, Window view, int wheelDeltaX, int wheelDeltaY,
       int detail, int screenX, int screenY, int clientX, int clientY,
@@ skipping 42 matching lines @@
       event._initMouseScrollEvent(type, canBubble, cancelable, view, detail,
           screenX, screenY, clientX, clientY, ctrlKey, altKey, shiftKey,
           metaKey, button, relatedTarget, axis);
     } else {
 $endif
       // Fallthrough for Dartium.
       event.$dom_initMouseEvent(type, canBubble, cancelable, view, detail,
           screenX, screenY, clientX, clientY, ctrlKey, altKey, shiftKey,
           metaKey, button, relatedTarget);
       event.$dom_initWebKitWheelEvent(wheelDeltaX,
-          (wheelDeltaY / 120).toInt(), // Chrome does an auto-convert to pixels.
+          wheelDeltaY ~/ 120, // Chrome does an auto-convert to pixels.
           view, screenX, screenY, clientX, clientY, ctrlKey, altKey, shiftKey,
           metaKey);
 $if DART2JS
     }
 $endif
 
     return event;
   }
 
 $!MEMBERS
@@ skipping 118 matching lines @@
 $else
   @DomName('WheelEvent.deltaX')
   num get deltaX => $dom_wheelDeltaX;
   @DomName('WheelEvent.deltaY')
   num get deltaY => $dom_wheelDeltaY;
   @DomName('WheelEvent.deltaMode')
   int get deltaMode => 0;
 
 $endif
 }