code: function makeElementUnselectable(element) {
        if (typeof element.onselectstart !== 'undefined') {
          element.onselectstart = fabric.util.falseFunction;
        }
        if (selectProp) {
          element.style[selectProp] = 'none';
        }
        else if (typeof element.unselectable == 'string') {
          element.unselectable = 'on';
        }
        return element;
      }
docs: Makes element unselectable
  @method makeElementUnselectable
  @memberOf fabric.util
  @param {HTMLElement} element Element to make unselectable
  @return {HTMLElement} Element that was passed in