Add Node CommonJS regiter build

This adds a build as a first-class export for legacy CommonJS registration
in Node.js. This will grow in complexity so it deserves its own module.

fixtures/flight/server/index.js

@@ -1,13 +1,7 @@
 'use strict';
 
-const url = require('url');
-
-require.extensions['.client.js'] = function(module, path) {
-  module.exports = {
-    $$typeof: Symbol.for('react.module.reference'),
-    name: url.pathToFileURL(path).href,
-  };
-};
+const register = require('react-transport-dom-webpack/node-register');
+register();
 
 const babelRegister = require('@babel/register');
 

packages/react-transport-dom-webpack/node-register.js

@@ -0,0 +1,10 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+export * from './src/ReactFlightWebpackNodeRegister';

packages/react-transport-dom-webpack/npm/node-register.js

@@ -0,0 +1,3 @@
+'use strict';
+
+module.exports = require('./cjs/react-transport-dom-webpack-node-register.js');

packages/react-transport-dom-webpack/package.json

@@ -17,6 +17,7 @@
     "server.js",
     "server.browser.js",
     "server.node.js",
+    "node-register.js",
     "cjs/",
     "esm/"
   ],
@@ -27,6 +28,7 @@
     "./server.browser": "./server.browser.js",
     "./server.node": "./server.node.js",
     "./node-loader": "./esm/react-transport-dom-webpack-node-loader.js",
+    "./node-register": "./node-register.js",
     "./package.json": "./package.json"
   },
   "browser": {

packages/react-transport-dom-webpack/src/ReactFlightWebpackNodeRegister.js

@@ -0,0 +1,19 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+const url = require('url');
+
+module.exports = function register() {
+  (require: any).extensions['.client.js'] = function(module, path) {
+    module.exports = {
+      $$typeof: Symbol.for('react.module.reference'),
+      name: url.pathToFileURL(path).href,
+    };
+  };
+};

scripts/rollup/bundles.js

@@ -295,6 +295,15 @@ const bundles = [
     externals: [],
   },
 
+  /******* React Transport DOM Webpack Node.js CommonJS Loader *******/
+  {
+    bundleTypes: [NODE_ES2015],
+    moduleType: RENDERER_UTILS,
+    entry: 'react-transport-dom-webpack/node-register',
+    global: 'ReactFlightWebpackNodeRegister',
+    externals: ['url'],
+  },
+
   /******* React Transport DOM Server Relay *******/
   {
     bundleTypes: [FB_WWW_DEV, FB_WWW_PROD],