ed correctly.
      if (this.opened) {
        this._openedChanged(this.opened);
      }
      this._observer = Polymer.dom(this).observeNodes(this._onNodesChange);
    },

    detached: function() {
      Polymer.dom(this).unobserveNodes(this._observer);
      this._observer = null;
      if (this.__raf) {
        window.cancelAnimationFrame(this.__raf);
        this.__raf = null;
      }
      this._manager.removeOverlay(this);
    },

    /**
     * Toggle the opened state of the overlay.
     */
    tog