code: function isReactNode(node) {
    return isValidContainer(node) && (node.hasAttribute(ROOT_ATTR_NAME) || node.hasAttribute(ATTR_NAME));
  }
docs: True if the supplied DOM node is a valid React node element.
  
  @param {?DOMElement} node The candidate DOM node.
  @return {boolean} True if the DOM is a valid React DOM node.
  @internal