Remove global babelHelpers and regenerator (#21283)

Summary:
Follow up to https://github.com/facebook/metro/commit/8932a9caa8f9ffe82160f2da25342a0bde3bbb26

Babel helpers and regenerator runtime will be imported automatically from `babel/runtime`. We still need to add the global regeneratorRuntime for jest tests since we disable babel-runtime currently.
Pull Request resolved: https://github.com/facebook/react-native/pull/21283

Reviewed By: mjesun

Differential Revision: D10010963

Pulled By: rafeca

fbshipit-source-id: da5e23dd901f8f8940d46816b4fc9290d0e28c76

IntegrationTests/RCTRootViewIntegrationTestApp.js

@@ -9,8 +9,6 @@
 
 'use strict';
 
-require('regenerator-runtime/runtime');
-
 const React = require('react');
 const ReactNative = require('react-native');
 

jest/setup.js

@@ -92,7 +92,6 @@ jest
   })
   .mock('ensureComponentIsNative', () => () => true);
 
-const mockEmptyObject = {};
 const mockNativeModules = {
   AlertManager: {
     alertWithArgs: jest.fn(),

package.json

@@ -149,6 +149,7 @@
     "react": "16.5.0"
   },
   "dependencies": {
+    "@babel/runtime": "^7.0.0",
     "absolute-path": "^0.0.0",
     "art": "^0.10.0",
     "base64-js": "^1.1.2",

rn-get-polyfills.js

@@ -18,5 +18,4 @@ module.exports = () => [
   require.resolve('./Libraries/polyfills/Array.prototype.es6.js'),
   require.resolve('./Libraries/polyfills/Array.es6.js'),
   require.resolve('./Libraries/polyfills/Object.es7.js'),
-  require.resolve('./Libraries/polyfills/babelHelpers.js'),
 ];