function hasScrollableSpace(el, axis) {
      if (axis === 'Y') {
        return el.clientHeight + ROUNDING_TOLERANCE < el.scrollHeight;
      }

      if (axis === 'X') {
        return el.clientWidth + ROUNDING_TOLERANCE < el.scrollWidth;
      }
    }
indicates if an element has scrollable space in the provided axis
@method hasScrollableSpace
@param {Node} el
@param {String} axis
@returns {Boolean}