code: function removeScrollerShadow(displayElement, scrollElement) {
          if (!scrollElement) {
              scrollElement = displayElement;
          }
  
          var $displayElement = $(displayElement),
              $scrollElement = $(scrollElement);
  
          // remove scrollerShadow elements from DOM
          $displayElement.find(".scroller-shadow.top").remove();
          $displayElement.find(".scroller-shadow.bottom").remove();
  
          // remove event handlers
          $scrollElement.off("scroll.scroller-shadow");
          $displayElement.off("contentChanged.scroller-shadow");
      }
docs: Remove scroller-shadow effect.
  @param {!DOMElement} displayElement the DOMElement that displays the shadow
  @param {?Object} scrollElement the object that is scrolled