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.
return (
      type === 'textarea' ||
      typeof props.children === 'string' ||
      typeof props.children === 'number' ||
      (typeof props.dangerouslySetInnerHTML === 'object' &&
        props.dangerouslySetInnerHTML !== null &&
        typeof props.dangerouslySetInnerHTML.__html === 'string')
    );
  },
  resetTextContent(domElement: Instance): void {
    domElement.textContent = '';
  },
  shouldDeprioritizeSubtree(type: string, props: Props): boolean {
    return !!props.hidden;
  },
  createTextInstance(
    text: string,
    rootContainerInstance: Container,
    hostContext: HostContext,
    internalInstanceHandle: Object,
  ): TextInstance {
    if (__DEV__) {
      const hostContextDev = ((hostContext: any): HostContextDev);
      validateDOMNesting(null, text, null, hostContextDev.ancestorInfo);
    }
    var textNode: TextInstance = document.createTextNode(text);
    precacheFiberNode(internalInstanceHandle, textNode);
    return textNode;
  },
  commitTextUpdate(