scrollListener = function scrollListener(e) {
      // Don't measure (which forces) reflow for scrolls that happen inside of children!
      if (e.target.className && typeof e.target.className.indexOf === 'function' && e.target.className.indexOf('contract-trigger') < 0 && e.target.className.indexOf('expand-trigger') < 0) {
        return;
      }

      var element = this;
      resetTriggers(this);

      if (this.__resizeRAF__) {
        cancelFrame(this.__resizeRAF__);
      }

      this.__resizeRAF__ = requestFrame(function () {
        if (checkTriggers(element)) {
          element.__resizeLast__.width = element.offsetWidth;
          element.__resizeLast__.height = element.offsetHeight;

          element.__resizeListeners__.forEach(function (fn) {
            fn.call(element, e);
          });
        }
      });
    }
Return a function that produces ReactElements of a given type.
See https://facebook.github.io/react/docs/top-level-api.html#react.createfactory