Clear fields on unmount of fiber to avoid memory leak (#14276)

* Clear fields on unmount of fiber to avoid memory leak

Author: trueadm

packages/react-reconciler/src/ReactFiberCommitWork.js

@@ -728,9 +728,14 @@ function detachFiber(current: Fiber) {
   // itself will be GC:ed when the parent updates the next time.
   current.return = null;
   current.child = null;
-  if (current.alternate) {
-    current.alternate.child = null;
-    current.alternate.return = null;
+  current.memoizedState = null;
+  current.updateQueue = null;
+  const alternate = current.alternate;
+  if (alternate !== null) {
+    alternate.return = null;
+    alternate.child = null;
+    alternate.memoizedState = null;
+    alternate.updateQueue = null;
   }
 }