Function isValidContainer

code/styling/public/app.js:17494–17496

* True if the supplied DOM node is a valid node element. * * @param {?DOMElement} node The candidate DOM node. * @return {boolean} True if the DOM is a valid DOM node. * @internal

(node)

 * @internal
 */
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 '));
}

function getReactRootElementInContainer(container) {
  if (!container) {