Revert "Clear more Fiber fields in detachFiber (#18556)" (#18562)

This reverts commit d48dbb8.

Author: gaearon

packages/react-reconciler/src/ReactFiberCommitWork.new.js

@@ -1118,7 +1118,6 @@ function detachFiber(fiber: Fiber) {
   // itself will be GC:ed when the parent updates the next time.
   fiber.return = null;
   fiber.child = null;
-  fiber.sibling = null;
   fiber.memoizedState = null;
   fiber.updateQueue = null;
   fiber.dependencies = null;
@@ -1128,9 +1127,6 @@ function detachFiber(fiber: Fiber) {
   fiber.pendingProps = null;
   fiber.memoizedProps = null;
   fiber.stateNode = null;
-  if (__DEV__) {
-    fiber._debugOwner = null;
-  }
 }
 
 function emptyPortalContainer(current: Fiber) {

packages/react-reconciler/src/ReactFiberCommitWork.old.js

@@ -1118,7 +1118,6 @@ function detachFiber(fiber: Fiber) {
   // itself will be GC:ed when the parent updates the next time.
   fiber.return = null;
   fiber.child = null;
-  fiber.sibling = null;
   fiber.memoizedState = null;
   fiber.updateQueue = null;
   fiber.dependencies = null;
@@ -1128,9 +1127,6 @@ function detachFiber(fiber: Fiber) {
   fiber.pendingProps = null;
   fiber.memoizedProps = null;
   fiber.stateNode = null;
-  if (__DEV__) {
-    fiber._debugOwner = null;
-  }
 }
 
 function emptyPortalContainer(current: Fiber) {