 enforce gesture recognizer order
      for (let i = 0, r; i < recognizers.length; i++) {
        r = recognizers[i];
        if (gs[r.name] && !handled[r.name]) {
          handled[r.name] = true;
          r[type](ev);
        }
      }
    },

    /**
     * @private
     * @param {Event} ev Event.
     */
    _handleTouchAction: function(ev) {
      let t = ev.changedTouches[0];
      let type = ev.type;
      if (type === 'touchstart') {
        POINTERSTATE.touch.x = t.clientX;
        POINTERSTATE.to