function updateMouseMovementPolyfillState(event) {
    if (event !== lastMouseEvent) {
      if (lastMouseEvent && event.type === 'mousemove') {
        lastMovementX = event.screenX - lastMouseEvent.screenX;
        lastMovementY = event.screenY - lastMouseEvent.screenY;
      } else {
        lastMovementX = 0;
        lastMovementY = 0;
      }

      lastMouseEvent = event;
    }
  }
@interface Event
@see http://www.w3.org/TR/DOM-Level-3-Events/