dren are "hidden" and cache in
       * private storage for later retrieval.
       *
       * @override
       */
      _setUnmanagedPropertyToNode(node, prop, value) {
        if (node.__hideTemplateChildren__ &&
            node.nodeType == Node.TEXT_NODE && prop == 'textContent') {
          node.__polymerTextContent__ = value;
        } else {
          super._setUnmanagedPropertyToNode(node, prop, value);
        }
      }
      /**
       * Find the parent model of this template instance.  The parent