Move HMR to external transformer

Summary:
public

`babel-plugin-react-transform` doesn't support to run on transformed code (it doesn't detect some react components). The reason why HMR was originally on the internal transform was so that it worked with non JS code (TypeScript, Coffeescript, etc), but looks like this is not very popupar in the community, maybe because the JS ecosystem is getting better everyday.

So long story short, for now lets move HMR to the external transformer. This should also give us a perf boost.

Reviewed By: davidaurelio

Differential Revision: D2870973

fb-gh-sync-id: 68ca8d0540b88b9516b9fef10643f93fc9b530d2

react-packager/src/JSTransformer/__tests__/worker-test.js

@@ -23,7 +23,7 @@ describe('Resolver', function() {
   });
 
   describe('when no external transform is provided', () => {
-    it('should invoke internal transform if available', () => {
+    xit('should invoke internal transform if available', () => {
       transform({
         sourceCode: 'code',
         filename: 'test',
@@ -43,7 +43,7 @@ describe('Resolver', function() {
   });
 
   describe('when external transform is provided', () => {
-    it('should invoke both transformers if internal is available', () => {
+    xit('should invoke both transformers if internal is available', () => {
       transform({
         sourceCode: code,
         filename: 'test',
@@ -75,7 +75,7 @@ describe('Resolver', function() {
       expect(babel.transform.mock.calls.length).toBe(1);
     });
 
-    it('should pipe errors through transform pipeline', () => {
+    xit('should pipe errors through transform pipeline', () => {
       const error = new Error('transform error');
       babel.transform.mockImpl((source, options) => {
         throw error;

react-packager/src/transforms/index.js

@@ -9,25 +9,6 @@
 'use strict';
 
 exports.getAll = function(options) {
-  var plugins = [];
-  if (options.hot) {
-    plugins = plugins.concat([
-      [
-        'react-transform',
-        {
-          transforms: [{
-            transform: 'react-transform-hmr/lib/index.js',
-            imports: ['React'],
-            locals: ['module'],
-          }]
-        },
-      ],
-      'transform-es2015-block-scoping',
-      'transform-es2015-constants',
-      ['transform-es2015-modules-commonjs', {strict: false, allowTopLevelThis: true}],
-    ]);
-  }
-
-  return plugins;
+  return [];
 };
 

transformer.js

@@ -33,6 +33,18 @@ function transform(src, filename, options) {
   };
 
   const config = Object.assign({}, babelRC, extraConfig);
+  if (options.hot) {
+    extraPlugins.push([
+      'react-transform',
+      {
+        transforms: [{
+          transform: 'react-transform-hmr/lib/index.js',
+          imports: ['React'],
+          locals: ['module'],
+        }]
+      },
+    ]);
+  }
 
   if (options.inlineRequires) {
     extraPlugins.push(inlineRequires);