disposeScrollable method
      
void
disposeScrollable()
      
     
    
    
Implementation
void disposeScrollable() {
  scrollListener = null;
  scrollablePointerListener = null;
  _scrollOffsetX = null;
  _scrollOffsetY = null;
  // Dispose clip layer.
  _clipRRectLayer.layer = null;
  _clipRectLayer.layer = null;
}