Attach instance handle to DOM in DEV for enableInternalInstanceMap (facebook#35341)

Continue attaching `internalInstanceKey` to DOM nodes in DEV. This
prevents breaking some internal dev tooling while we experiment with the
broader change. Note that this does not reference the DOM handle within
the flag, just attaches it and deletes it. Internals tracking is still
done through the private map.

Author: jackpope

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

@@ -75,6 +75,9 @@ export function detachDeletedInstance(node: Instance): void {
     delete (node: any)[internalEventHandlerListenersKey];
     delete (node: any)[internalEventHandlesSetKey];
     delete (node: any)[internalRootNodeResourcesKey];
+    if (__DEV__) {
+      delete (node: any)[internalInstanceKey];
+    }
     return;
   }
   // TODO: This function is only called on host components. I don't think all of
@@ -97,6 +100,9 @@ export function precacheFiberNode(
 ): void {
   if (enableInternalInstanceMap) {
     internalInstanceMap.set(node, hostInst);
+    if (__DEV__) {
+      (node: any)[internalInstanceKey] = hostInst;
+    }
     return;
   }
   (node: any)[internalInstanceKey] = hostInst;