Track subtreeFlags et al with bubbleProperties

Original PR: facebook#19836

Author: acdlite

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

@@ -28,7 +28,7 @@ import {
   enableFundamentalAPI,
   enableScopeAPI,
 } from 'shared/ReactFeatureFlags';
-import {NoFlags, Placement} from './ReactFiberFlags';
+import {NoFlags, Placement, StaticMask} from './ReactFiberFlags';
 import {ConcurrentRoot, BlockingRoot} from './ReactRootTags';
 import {
   IndeterminateComponent,
@@ -299,6 +299,9 @@ export function createWorkInProgress(current: Fiber, pendingProps: any): Fiber {
     }
   }
 
+  // Reset all effects except static ones.
+  // Static effects are not specific to a render.
+  workInProgress.flags = current.flags & StaticMask;
   workInProgress.childLanes = current.childLanes;
   workInProgress.lanes = current.lanes;
 

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

@@ -63,6 +63,7 @@ import {
   Deletion,
   ChildDeletion,
   ForceUpdateForLegacySuspense,
+  StaticMask,
 } from './ReactFiberFlags';
 import ReactSharedInternals from 'shared/ReactSharedInternals';
 import {
@@ -2092,6 +2093,12 @@ function updateSuspenseFallbackChildren(
       currentPrimaryChildFragment,
       primaryChildProps,
     );
+
+    // Since we're reusing a current tree, we need to reuse the flags, too.
+    // (We don't do this in legacy mode, because in legacy mode we don't re-use
+    // the current tree; see previous branch.)
+    primaryChildFragment.subtreeFlags =
+      currentPrimaryChildFragment.subtreeFlags & StaticMask;
   }
   let fallbackChildFragment;
   if (currentFallbackChildFragment !== null) {