Silence assert triggered by background executor race condition (#40895)

Summary:
Pull Request resolved: #40895

This is a long running debug assert due to a race condition with BE. I have at times wanted to try to add a lock to protect this, and measure impact, but really it will go away when we get rid of BE anyway, and any strategy I have come up with to lock gets hairy quickly.

This change does not impact RN in OSS, where BE is already disabled.

Changelog: [Internal]

Reviewed By: rshest

Differential Revision: D50247680

fbshipit-source-id: d004fc7db24f1f0b7c3ea8756d4678ce41579712

Author: NickGerleman

packages/react-native/ReactCommon/react/renderer/components/view/YogaLayoutableShadowNode.cpp

@@ -106,14 +106,20 @@ YogaLayoutableShadowNode::YogaLayoutableShadowNode(
       yogaConfig_(FabricDefaultYogaLog),
       yogaNode_(static_cast<const YogaLayoutableShadowNode&>(sourceShadowNode)
                     .yogaNode_) {
-  // Note, cloned `yoga::Node` instance (copied using copy-constructor) inherits
-  // dirty flag, measure function, and other properties being set originally in
-  // the `YogaLayoutableShadowNode` constructor above.
-
+// Note, cloned `yoga::Node` instance (copied using copy-constructor) inherits
+// dirty flag, measure function, and other properties being set originally in
+// the `YogaLayoutableShadowNode` constructor above.
+
+// There is a known race condition when background executor is enabled, where
+// a tree may be laid out on the Fabric background thread concurrently with
+// the ShadowTree being created on the JS thread. This assert can be
+// re-enabled after disabling background executor everywhere.
+#if 0
   react_native_assert(
       static_cast<const YogaLayoutableShadowNode&>(sourceShadowNode)
               .yogaNode_.isDirty() == yogaNode_.isDirty() &&
       "Yoga node must inherit dirty flag.");
+#endif
 
   if (!getTraits().check(ShadowNodeTraits::Trait::LeafYogaNode)) {
     for (auto& child : getChildren()) {