Don't clear static flags in resetWorkInProgress

Fixes the regression test added in facebook#20433

Author: acdlite

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

@@ -365,7 +365,7 @@ export function resetWorkInProgress(workInProgress: Fiber, renderLanes: Lanes) {
 
   // Reset the effect flags but keep any Placement tags, since that's something
   // that child fiber is setting, not the reconciliation.
-  workInProgress.flags &= Placement;
+  workInProgress.flags &= StaticMask | Placement;
 
   // The effect list is no longer valid.
   workInProgress.nextEffect = null;

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

@@ -363,9 +363,9 @@ export function resetWorkInProgress(workInProgress: Fiber, renderLanes: Lanes) {
   // We assume pendingProps, index, key, ref, return are still untouched to
   // avoid doing another reconciliation.
 
-  // Reset the effect tag but keep any Placement tags, since that's something
+  // Reset the effect flags but keep any Placement tags, since that's something
   // that child fiber is setting, not the reconciliation.
-  workInProgress.flags &= Placement;
+  workInProgress.flags &= StaticMask | Placement;
 
   // The effect list is no longer valid.
   workInProgress.nextEffect = null;