Change ReactVersion from CJS to ES module

Author: sebmarkbage

packages/shared/ReactVersion.js

@@ -5,7 +5,5 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-'use strict';
-
 // TODO: this is special because it gets imported during build.
-module.exports = '16.13.0';
+export default '16.13.0';

scripts/release/publish-commands/update-stable-version-numbers.js

@@ -44,7 +44,7 @@ const run = async ({cwd, packages, skipPackages, tags}) => {
     const sourceReactVersion = readFileSync(
       sourceReactVersionPath,
       'utf8'
-    ).replace(/module\.exports = '[^']+';/, `module.exports = '${version}';`);
+    ).replace(/export default '[^']+';/, `export default '${version}';`);
     writeFileSync(sourceReactVersionPath, sourceReactVersion);
   }
 };

scripts/release/utils.js

@@ -209,10 +209,7 @@ const updateVersionsForNext = async (cwd, reactVersion, version) => {
   const sourceReactVersion = readFileSync(
     sourceReactVersionPath,
     'utf8'
-  ).replace(
-    /module\.exports = '[^']+';/,
-    `module.exports = '${reactVersion}';`
-  );
+  ).replace(/export default '[^']+';/, `export default '${reactVersion}';`);
   writeFileSync(sourceReactVersionPath, sourceReactVersion);
 
   // Update the root package.json.