Function createLegacyRoot

docs/external/js/react-dom.development.js:24771–24773

(container, options)

    return root;
  }
  function createLegacyRoot(container, options) {
    return new ReactDOMBlockingRoot(container, LegacyRoot, options);
  }
  function isValidContainer(node) {
    return !!(node && (node.nodeType === ELEMENT_NODE || node.nodeType === DOCUMENT_NODE || node.nodeType === DOCUMENT_FRAGMENT_NODE || node.nodeType === COMMENT_NODE && node.nodeValue === ' react-mount-point-unstable '));
  }