Shallow renderer and test utils bundles (#9426)

Shallow renderer and test utils bundles

Adds new bundles introduced with React 15.5 release to master (and 16 alpha)

react-dom/test-utils:

This new bundle contains what used to be react-addons-test-utils. This bundle shares things from react-dom rather than duplicates them.

A temporary createRenderer method has been left behind as a way to access the new shallow renderer. This is for the ReactNative release cycle only and should be going away before the final release.

react-test-renderer/shallow:

This new shallow renderer is almost entirely stand-alone (in that it doesn't use the React reconciler or scheduler). The only touch points are ReactElement and prop/context validation. This renderer is stack and fiber compatible.

src/node_modules/react-test-renderer/index.js

@@ -6,4 +6,4 @@
 
 'use strict';
 
-module.exports = require('checkPropTypes');
+module.exports = require('ReactTestRenderer');