code: function (forwardToLast) {
          var animators = this.animators;
          var len = animators.length;
          for (var i = 0; i < len; i++) {
              animators[i].stop(forwardToLast);
          }
          animators.length = 0;
  
          return this;
      }
docs: 停止动画
  @param {boolean} forwardToLast If move to last frame before stop