Don't clear other flags when adding Deletion

Same as facebook#20398 but for Deletions. There's no new regression test, but in
the effects refactor, existing tests will fail without this.

Author: acdlite

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

@@ -13,7 +13,12 @@ import type {Fiber} from './ReactInternalTypes';
 import type {Lanes} from './ReactFiberLane.new';
 
 import getComponentName from 'shared/getComponentName';
-import {Deletion, ChildDeletion, Placement} from './ReactFiberFlags';
+import {
+  Deletion,
+  ChildDeletion,
+  Placement,
+  StaticMask,
+} from './ReactFiberFlags';
 import {
   getIteratorFn,
   REACT_ELEMENT_TYPE,
@@ -275,7 +280,7 @@ function ChildReconciler(shouldTrackSideEffects) {
       returnFiber.firstEffect = returnFiber.lastEffect = childToDelete;
     }
     childToDelete.nextEffect = null;
-    childToDelete.flags = Deletion;
+    childToDelete.flags = (childToDelete.flags & StaticMask) | Deletion;
 
     let deletions = returnFiber.deletions;
     if (deletions === null) {

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

@@ -2007,7 +2007,8 @@ function updateSuspensePrimaryChildren(
   if (currentFallbackChildFragment !== null) {
     // Delete the fallback child fragment
     currentFallbackChildFragment.nextEffect = null;
-    currentFallbackChildFragment.flags = Deletion;
+    currentFallbackChildFragment.flags =
+      (currentFallbackChildFragment.flags & StaticMask) | Deletion;
     workInProgress.firstEffect = workInProgress.lastEffect = currentFallbackChildFragment;
     let deletions = workInProgress.deletions;
     if (deletions === null) {
@@ -2998,7 +2999,7 @@ function remountFiber(
       returnFiber.firstEffect = returnFiber.lastEffect = current;
     }
     current.nextEffect = null;
-    current.flags = Deletion;
+    current.flags = (current.flags & StaticMask) | Deletion;
 
     let deletions = returnFiber.deletions;
     if (deletions === null) {

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

@@ -24,7 +24,13 @@ import {
   HostRoot,
   SuspenseComponent,
 } from './ReactWorkTags';
-import {Deletion, ChildDeletion, Placement, Hydrating} from './ReactFiberFlags';
+import {
+  Deletion,
+  ChildDeletion,
+  Placement,
+  Hydrating,
+  StaticMask,
+} from './ReactFiberFlags';
 import invariant from 'shared/invariant';
 
 import {
@@ -124,7 +130,7 @@ function deleteHydratableInstance(
   const childToDelete = createFiberFromHostInstanceForDeletion();
   childToDelete.stateNode = instance;
   childToDelete.return = returnFiber;
-  childToDelete.flags = Deletion;
+  childToDelete.flags = (childToDelete.flags & StaticMask) | Deletion;
 
   // This might seem like it belongs on progressedFirstDeletion. However,
   // these children are not part of the reconciliation list of children.