function ScrollAnimationLoop(options, callback) {
    ScrollAnimationLoop_classCallCheck(this, ScrollAnimationLoop);
    this._parseOptions(options);
    if (typeof callback === 'function') {
      this.callback = callback;
    }
    this.direction = 'none';
    this.position = this.getPosition();
    this.lastAction = this._getTimestamp();
    this._startRun();
    this._boundListener = this._didScroll.bind(this);
    this.element.addEventListener('scroll', this._boundListener);
  }
ScrollAnimationLoop constructor.
Starts a requestAnimationFrame loop as long as the user has scrolled the scrollElement. Stops after a certain time.

@param {DefaultOptions.scroll} [options=DefaultOptions.scroll] options The options for the loop
@param {ScrollCallback} callback [loop=null] The loop callback