stResizeNotifications: function(event) {
      var target = event.path ? event.path[0] : event.target;

      if (target === this) {
        return;
      }

      if (this._interestedResizables.indexOf(target) === -1) {
        this._interestedResizables.push(target);
        this.listen(target, 'iron-resize', '_onDescendantIronResize');
      }

      target.assignParentResizable(this);
      this._notifyDescendant(target);

      event.stopPropagation();
    },

    _parentResizableChanged: function(pare