Add feature flag to use microtasks in the React Native Fabric renderer

Author: rubennorte

packages/react-native-renderer/src/ReactFiberConfigFabric.js

@@ -48,7 +48,7 @@ const {
   unstable_getCurrentEventPriority: fabricGetCurrentEventPriority,
 } = nativeFabricUIManager;
 
-import {diffInCommitPhase} from 'shared/ReactFeatureFlags';
+import {diffInCommitPhase, useMicrotasksForSchedulingInNative} from 'shared/ReactFeatureFlags';
 
 const {get: getViewConfigForType} = ReactNativeViewConfigRegistry;
 
@@ -122,7 +122,6 @@ export * from 'react-reconciler/src/ReactFiberConfigWithNoMutation';
 export * from 'react-reconciler/src/ReactFiberConfigWithNoHydration';
 export * from 'react-reconciler/src/ReactFiberConfigWithNoScopes';
 export * from 'react-reconciler/src/ReactFiberConfigWithNoTestSelectors';
-export * from 'react-reconciler/src/ReactFiberConfigWithNoMicrotasks';
 export * from 'react-reconciler/src/ReactFiberConfigWithNoResources';
 export * from 'react-reconciler/src/ReactFiberConfigWithNoSingletons';
 
@@ -499,3 +498,9 @@ export function waitForCommitToBeReady(): null {
 }
 
 export const NotPendingTransition: TransitionStatus = null;
+
+// -------------------
+//     Microtasks
+// -------------------
+export const supportsMicrotasks = useMicrotasksForSchedulingInNative;
+export const scheduleMicrotask: any = typeof queueMicrotask === 'function' ? queueMicrotask : scheduleTimeout;

packages/shared/ReactFeatureFlags.js

@@ -125,6 +125,8 @@ export const enableAsyncActions = __EXPERIMENTAL__;
 
 export const alwaysThrottleRetries = true;
 
+export const useMicrotasksForSchedulingInNative = false;
+
 // -----------------------------------------------------------------------------
 // Chopping Block
 //

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

@@ -21,6 +21,7 @@ export const {
   enableUseRefAccessWarning,
   enableDeferRootSchedulingToMicrotask,
   alwaysThrottleRetries,
+  useMicrotasksForSchedulingInNative,
 } = dynamicFlags;
 
 // The rest of the flags are static for better dead code elimination.