Currently if React is not loaded, ReactDOM shows this:

<img width="664" alt="screen shot 2017-08-08 at 3 36 52 pm" src="https://user-images.githubusercontent.com/810438/29077217-784c7624-7c4f-11e7-88bc-b055407523a9.png">

We should throw a nicer error message in the entry point I think.
unstable_createPortal(
    children: ReactNodeList,
    container: DOMContainer,
    key: ?string = null,
  ) {
    
    return ReactPortal.createPortal(children, container, null, key);
  },
  unstable_batchedUpdates: ReactGenericBatching.batchedUpdates,
  unstable_deferredUpdates: DOMRenderer.deferredUpdates,
  flushSync: DOMRenderer.flushSync,
  __SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: {
    
    EventPluginHub: require('EventPluginHub'),
    
    EventPluginRegistry: require('EventPluginRegistry'),
    EventPropagators: require('EventPropagators'),
    ReactControlledComponent,
    ReactDOMComponentTree,
    ReactDOMEventListener: require('ReactDOMEventListener'),
  },
};
const foundDevTools = injectInternals({
  findFiberByHostInstance: ReactDOMComponentTree.getClosestInstanceFromNode,
  findHostInstanceByFiber: DOMRenderer.findHostInstance,
  
  bundleType: __DEV__ ? 1 : 0,
  version: ReactVersion,
});
if (__DEV__) {