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.
Array.prototype.indexOf,
      Array.prototype.map,
      Date.now,
      Function.prototype.bind,
      Object.keys,
      String.prototype.trim,
    ];
    for (var i = 0; i < expectedFeatures.length; i++) {
      if (!expectedFeatures[i]) {
        warning(
          false,
          'One or more ES5 shims expected by React are not available: ' +
            'https://fb.me/react-warning-polyfills',
        );
        break;
      }
    }
  }
}
if (__DEV__) {
  var ReactInstrumentation = require('ReactInstrumentation');
  var ReactDOMUnknownPropertyHook = require('ReactDOMUnknownPropertyHook');
  var ReactDOMNullInputValuePropHook = require('ReactDOMNullInputValuePropHook');
  var ReactDOMInvalidARIAHook = require('ReactDOMInvalidARIAHook');
  ReactInstrumentation.debugTool.addHook(ReactDOMUnknownPropertyHook);
  ReactInstrumentation.debugTool.addHook(ReactDOMNullInputValuePropHook);
  ReactInstrumentation.debugTool.addHook(ReactDOMInvalidARIAHook);
}
module.exports = ReactDOMStack;