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

sdk/lib/html/dart2js/html_dart2js.dart

 library html;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:html_common';
 import 'dart:indexed_db';
 import 'dart:isolate';
 import 'dart:json' as json;
 import 'dart:math';
 import 'dart:svg' as svg;
@@ skipping 22413 matching lines @@
       }
       event._initMouseScrollEvent(type, canBubble, cancelable, view, detail,
           screenX, screenY, clientX, clientY, ctrlKey, altKey, shiftKey,
           metaKey, button, relatedTarget, axis);
     } else {
       // 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);
     }
 
     return event;
   }
 
 
   @DocsEditable @DomName('WheelEvent.webkitDirectionInvertedFromDevice')
   final bool webkitDirectionInvertedFromDevice;
@@ skipping 6393 matching lines @@
       _position = nextPosition;
       return true;
     }
     _current = null;
     _position = _array.length;
     return false;
   }
 
   T get current => _current;
 }