avoid the cost of cloning nested template content).
       *
       * @param {HTMLTemplateElement} node Node to parse (a <template>)
       * @param {Object} outerTemplateInfo Template metadata for current template
       *   that includes the template `node`
       * @param {Object} nodeInfo Node metadata for current template.
       * @return {boolean} `true` if the visited node added node-specific
       *   metadata to `nodeInfo`
       */
      static _parseTemplateNestedTemplate(node, outerTemplateInf