Remove ReactDOM.native shim

This is causing build errors.

This should be in the downstream repo if anything.

Relay has its own shim that should be preferred.

packages/react/lib/ReactDOM.native.js

@@ -1,16 +0,0 @@
-/**
- * @providesModule ReactDOM
- */
-
-'use strict';
-
-var ReactUpdates = require('./ReactUpdates');
-
-// TODO: In React Native, ReactTestUtils depends on ./ReactDOM (for
-// renderIntoDocument, which should never be called) and Relay depends on
-// react-dom (for batching). Once those are fixed, nothing in RN should import
-// this module and this file can go away.
-
-module.exports = {
-  unstable_batchedUpdates: ReactUpdates.batchedUpdates,
-};