[RN] Use microtasks when using bridgeless mode in React Native Fabric renderer (OSS version)

Author: rubennorte

.eslintrc.js

@@ -533,5 +533,7 @@ module.exports = {
     AsyncLocalStorage: 'readonly',
     async_hooks: 'readonly',
     globalThis: 'readonly',
+
+    RN$Bridgeless: 'readonly',
   },
 };

packages/shared/forks/ReactFeatureFlags.native-oss.js

@@ -82,7 +82,10 @@ export const enableAsyncActions = false;
 
 export const alwaysThrottleRetries = false;
 
-export const useMicrotasksForSchedulingInFabric = false;
+const isBridgeless: boolean =
+  typeof RN$Bridgeless !== 'undefined' && !!RN$Bridgeless;
+
+export const useMicrotasksForSchedulingInFabric = isBridgeless;
 export const passChildrenWhenCloningPersistedNodes = false;
 export const enableUseDeferredValueInitialArg = __EXPERIMENTAL__;
 export const disableClientCache = true;

scripts/flow/xplat.js

@@ -7,6 +7,9 @@
  * @flow
  */
 
+// eslint-disable-next-line no-unused-vars
+declare const RN$Bridgeless: boolean;
+
 declare module 'ReactNativeInternalFeatureFlags' {
   declare export var alwaysThrottleRetries: boolean;
   declare export var enableComponentStackLocations: boolean;

scripts/rollup/validate/eslintrc.rn.js

@@ -42,6 +42,8 @@ module.exports = {
     // Fabric. See https://github.com/facebook/react/pull/15490
     // for more information
     nativeFabricUIManager: 'readonly',
+    // RN Bridgeless mode flag
+    RN$Bridgeless: 'readonly',
     // Trusted Types
     trustedTypes: 'readonly',
     // RN supports this