Use "babel-preset-react-native"

Summary:
Rather than specifying Babel plugins in the `.babelrc` packaged with react-native, leverage a Babel preset to define the plugins (https://github.com/exponentjs/babel-preset-react-native).

This allows for a much better user experience for those who want (or need) to override options in their project's `.babelrc`.

Prior to this PR, if a user wanted to use a custom babel-plugin (or a custom set of babel plugins), they'd have either 1) manually override the `.babelrc` in the react-packager directory (or fork RN), or 2) specify a custom transformer to use when running the packager that loaded their own `.babelrc`. Note - the custom transformer was necessary because without it, RN's `.babelrc` options would supersede the options defined in the project's `.babelrc`...potentially causing issues with plugin ordering.

This PR makes the transformer check for the existence of a project-level `.babelrc`, and if it it's there, it _doesn't_ use the react-native `.babelrc`. This prevents any oddities with Babel plug
Closes https://github.com/facebook/react-native/pull/5214

Reviewed By: davidaurelio

Differential Revision: D2881814

Pulled By: martinbigio

fb-gh-sync-id: 4168144b7a365fae62bbeed094d8a03a48b4798c

packager/react-packager/.babelrc

@@ -1,30 +0,0 @@
-{
-  "retainLines": true,
-  "compact": true,
-  "comments": false,
-  "plugins": [
-    "syntax-async-functions",
-    "syntax-class-properties",
-    "syntax-trailing-function-commas",
-    "transform-class-properties",
-    "transform-es2015-arrow-functions",
-    "transform-es2015-block-scoping",
-    "transform-es2015-classes",
-    "transform-es2015-computed-properties",
-    "transform-es2015-constants",
-    "transform-es2015-destructuring",
-    ["transform-es2015-modules-commonjs", {"strict": false, "allowTopLevelThis": true}],
-    "transform-es2015-parameters",
-    "transform-es2015-shorthand-properties",
-    "transform-es2015-spread",
-    "transform-es2015-template-literals",
-    "transform-flow-strip-types",
-    "transform-object-assign",
-    "transform-object-rest-spread",
-    "transform-react-display-name",
-    "transform-react-jsx",
-    "transform-regenerator",
-    "transform-es2015-for-of"
-  ],
-  "sourceMaps": false
-}

packager/react-packager/index.js

@@ -15,7 +15,6 @@ useGracefulFs();
 var debug = require('debug');
 var omit = require('underscore').omit;
 var Activity = require('./src/Activity');
-var Transforms = require('./src/transforms');
 
 exports.createServer = createServer;
 exports.middleware = function(options) {
@@ -24,7 +23,6 @@ exports.middleware = function(options) {
 };
 
 exports.Activity = Activity;
-exports.getTransforms = Transforms.getAll;
 
 // Renamed "package" to "bundle". But maintain backwards
 // compat.

packager/react-packager/rn-babelrc.json

@@ -0,0 +1,4 @@
+{
+  "presets": [ "react-native" ],
+  "plugins": []
+}

packager/react-packager/src/JSTransformer/index.js

@@ -66,6 +66,7 @@ class Transformer {
 
     this._cache = opts.cache;
     this._transformModulePath = opts.transformModulePath;
+    this._projectRoots = opts.projectRoots;
 
     if (opts.transformModulePath != null) {
       let transformer;
@@ -129,6 +130,7 @@ class Transformer {
             filename: filePath,
             options: {
               ...options,
+              projectRoots: this._projectRoots,
               externalTransformModulePath: this._transformModulePath,
             },
           }).then(res => {

packager/react-packager/src/JSTransformer/resolvePlugins.js

@@ -1,32 +0,0 @@
-/**
- * Copyright (c) 2015-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- */
-'use strict';
-
-/**
- * Manually resolve all default Babel plugins.
- * `babel.transform` will attempt to resolve all base plugins relative to
- * the file it's compiling. This makes sure that we're using the plugins
- * installed in the react-native package.
- */
-function resolvePlugins(plugins) {
-  return plugins.map(function(plugin) {
-    // Normalise plugin to an array.
-    if (!Array.isArray(plugin)) {
-      plugin = [plugin];
-    }
-    // Only resolve the plugin if it's a string reference.
-    if (typeof plugin[0] === 'string') {
-      plugin[0] = require('babel-plugin-' + plugin[0]);
-      plugin[0] = plugin[0].__esModule ? plugin[0].default : plugin[0];
-    }
-    return plugin;
-  });
-}
-
-module.exports = resolvePlugins;

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

@@ -9,30 +9,25 @@
 'use strict';
 
 var babel = require('babel-core');
-var resolvePlugins = require('./resolvePlugins');
-var Transforms = require('../transforms');
+var makeInternalConfig = require('babel-preset-react-native/configs/internal');
 
 // Runs internal transforms on the given sourceCode. Note that internal
 // transforms should be run after the external ones to ensure that they run on
 // Javascript code
 function internalTransforms(sourceCode, filename, options) {
-  var plugins = resolvePlugins(Transforms.getAll(options));
-  if (plugins.length === 0) {
+  var internalBabelConfig = makeInternalConfig(options);
+
+  if (!internalBabelConfig) {
     return {
       code: sourceCode,
       filename: filename,
     };
   }
 
-  var result = babel.transform(sourceCode, {
-    retainLines: true,
-    compact: true,
-    comments: false,
+  var result = babel.transform(sourceCode, Object.assign({
     filename: filename,
     sourceFileName: filename,
-    sourceMaps: false,
-    plugins: plugins,
-  });
+  }, internalBabelConfig));
 
   return {
     code: result.code,

packager/react-packager/src/Resolver/index.js

@@ -93,7 +93,6 @@ class Resolver {
         // should work after this release and we can
         // remove it from here.
         'parse',
-        'react-transform-hmr',
       ],
       platforms: ['ios', 'android'],
       preferNativePlatform: true,

packager/react-packager/src/transforms/index.js

@@ -1,14 +0,0 @@
-/**
- * Copyright (c) 2015-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- */
-'use strict';
-
-exports.getAll = function(options) {
-  return [];
-};
-