Don't load 'babel-polyfill', only polyfill `Array#values`, `Object.values`, and `Object.entries`

Summary:Instead of loading `'babel-polyfill'` into packager, we only polyfill es6 methods that are unavailable in node 4, and es7 stage 4 proposals.
That makes sure that we are using native promises, and don't load unnecessary polyfills.

Reviewed By: vjeux

Differential Revision: D3168057

fb-gh-sync-id: 68b53795d9a1d7cfdc00fc31684da3ad21a7bb34
fbshipit-source-id: 68b53795d9a1d7cfdc00fc31684da3ad21a7bb34

packager/babelRegisterOnly.js

@@ -8,7 +8,9 @@
  */
 'use strict';
 
-require('babel-polyfill');
+Array.prototype.values || require('core-js/fn/array/values');
+Object.entries || require('core-js/fn/object/entries');
+Object.values || require('core-js/fn/object/values');
 
 var fs = require('fs');
 var path = require('path');