Fix moveBefore feature detection (facebook#32087)

`moveBefore` was moved to the `ParentNode` mixin as per
whatwg/dom#1307 (comment) _(and was
committed in
whatwg/dom@3f3e94c5beda922962dacaeb606087f57bd7f7be)_

As a result, its existence can no longer be checked on `Node.prototype`
but must be checked in `Element.prototype`

Author: bramus

packages/react-dom-bindings/src/client/ReactFiberConfigDOM.js

@@ -780,7 +780,7 @@ const supportsMoveBefore =
   // $FlowFixMe[prop-missing]: We're doing the feature detection here.
   enableMoveBefore &&
   typeof window !== 'undefined' &&
-  typeof window.Node.prototype.moveBefore === 'function';
+  typeof window.Element.prototype.moveBefore === 'function';
 
 export function appendChild(
   parentInstance: Instance,