Don't re-export react-scheduler APIs for CJS bundles

.eslintrc.js

@@ -84,5 +84,6 @@ module.exports = {
     spyOnDevAndProd: true,
     spyOnProd: true,
     __PROFILE__: true,
+    __UMD__: true,
   },
 };

packages/react/src/ReactSharedInternals.js

@@ -31,28 +31,35 @@ const ReactSharedInternals = {
   ReactCurrentOwner,
   // Used by renderers to avoid bundling object-assign twice in UMD bundles:
   assign,
+};
+
+if (__UMD__) {
   // Re-export the react-scheduler API(s) for UMD bundles.
   // This avoids introducing a dependency on a new UMD global in a minor update,
   // Since that would be a breaking change (e.g. for all existing CodeSandboxes).
-  Scheduler: {
-    cancelScheduledWork,
-    now,
-    scheduleWork,
-  },
-  SchedulerTracking: {
-    __getInteractionsRef,
-    __getSubscriberRef,
-    clear,
-    getCurrent,
-    getThreadID,
-    track,
-    wrap,
-  },
-  SchedulerTrackingSubscriptions: {
-    subscribe,
-    unsubscribe,
-  },
-};
+  // This re-export is only required for UMD bundles;
+  // CJS bundles use the shared NPM package.
+  Object.assign(ReactSharedInternals, {
+    Scheduler: {
+      cancelScheduledWork,
+      now,
+      scheduleWork,
+    },
+    SchedulerTracking: {
+      __getInteractionsRef,
+      __getSubscriberRef,
+      clear,
+      getCurrent,
+      getThreadID,
+      track,
+      wrap,
+    },
+    SchedulerTrackingSubscriptions: {
+      subscribe,
+      unsubscribe,
+    },
+  });
+}
 
 if (__DEV__) {
   Object.assign(ReactSharedInternals, {

scripts/flow/environment.js

@@ -10,6 +10,7 @@
 /* eslint-disable */
 
 declare var __PROFILE__: boolean;
+declare var __UMD__: boolean;
 
 declare var __REACT_DEVTOOLS_GLOBAL_HOOK__: any; /*?{
   inject: ?((stuff: Object) => void)

scripts/jest/setupEnvironment.js

@@ -6,6 +6,7 @@ if (NODE_ENV !== 'development' && NODE_ENV !== 'production') {
 }
 global.__DEV__ = NODE_ENV === 'development';
 global.__PROFILE__ = NODE_ENV === 'development';
+global.__UMD__ = false;
 
 if (typeof window !== 'undefined') {
   global.requestAnimationFrame = function(callback) {

scripts/rollup/build.js

@@ -325,6 +325,7 @@ function getPlugins(
     replace({
       __DEV__: isProduction ? 'false' : 'true',
       __PROFILE__: isProfiling || !isProduction ? 'true' : 'false',
+      __UMD__: isUMDBundle ? 'true' : 'false',
       'process.env.NODE_ENV': isProduction ? "'production'" : "'development'",
     }),
     // We still need CommonJS for external deps like object-assign.