Bug 1312236 updated React to v15.3.2 which was making webconsole's mocha test fail.
An error was thrown because the path and export we do in requireHelper to make enzyme
able to call React functions was changed.
We fix the require to ReactDOM by using the react-dom.js file, and we add the similar
react-dom-server.js for ReactDOMServer functions.
Tests now run like they used to.
MozReview-Commit-ID: GXIQJPlqp4A
