to let them do their thing
        // before we walk them.
        this.async(function() {
          this.$.selection.routes = this._routesFromChildren();
          this._observeManagedSelector();
        });
      },

      selectedIndexChanged: function() {
        if (!this.routingIsReady || !this._managedSelector) return;
        this._managedSelector.selected = this.selectedIndex;
      },

      /**
       * Are we managing a `core-selector`?
       */
      _findChildSelector: function() {
        if