Put createRoot export under a feature flag (#11426)

packages/react-cs-renderer/src/ReactNativeCSFeatureFlags.js

@@ -13,6 +13,7 @@ var ReactNativeCSFeatureFlags: FeatureFlags = {
   enableAsyncSubtreeAPI: true,
   enableAsyncSchedulingByDefaultInReactDOM: false,
   enableReactFragment: false,
+  enableCreateRoot: false,
   // React Native CS uses persistent reconciler.
   enableMutatingReconciler: false,
   enableNoopReconciler: false,

packages/react-dom/src/__tests__/ReactDOMRoot-test.js

@@ -9,6 +9,7 @@
 
 'use strict';
 
+require('shared/ReactFeatureFlags').enableCreateRoot = true;
 var React = require('react');
 var ReactDOM = require('react-dom');
 var ReactDOMServer = require('react-dom/server');

packages/react-dom/src/client/ReactDOM.js

@@ -787,12 +787,7 @@ ReactRoot.prototype.unmount = function(callback) {
   DOMRenderer.updateContainer(null, root, null, callback);
 };
 
-var ReactDOM = {
-  createRoot(container: DOMContainer, options?: RootOptions): ReactRootNode {
-    const hydrate = options != null && options.hydrate === true;
-    return new ReactRoot(container, hydrate);
-  },
-
+var ReactDOM: Object = {
   createPortal,
 
   findDOMNode(
@@ -952,6 +947,16 @@ var ReactDOM = {
   },
 };
 
+if (ReactFeatureFlags.enableCreateRoot) {
+  ReactDOM.createRoot = function createRoot(
+    container: DOMContainer,
+    options?: RootOptions,
+  ): ReactRootNode {
+    const hydrate = options != null && options.hydrate === true;
+    return new ReactRoot(container, hydrate);
+  };
+}
+
 const foundDevTools = injectInternals({
   findFiberByHostInstance: ReactDOMComponentTree.getClosestInstanceFromNode,
   findHostInstanceByFiber: DOMRenderer.findHostInstance,

packages/shared/ReactFeatureFlags.js

@@ -14,6 +14,7 @@ export type FeatureFlags = {|
   enableNoopReconciler: boolean,
   enablePersistentReconciler: boolean,
   enableReactFragment: boolean,
+  enableCreateRoot: boolean,
 |};
 
 var ReactFeatureFlags: FeatureFlags = {
@@ -27,6 +28,8 @@ var ReactFeatureFlags: FeatureFlags = {
   enablePersistentReconciler: false,
   // Exports React.Fragment
   enableReactFragment: false,
+  // Exports ReactDOM.createRoot
+  enableCreateRoot: false,
 };
 
 if (__DEV__) {