Observed this on react@16.0.0-beta.5

```js
import React from 'react';
import { renderToString } from 'react-dom/server';

const B = () => 'b';

console.log(renderToString(<div>{'a'}<B />{'c'}</div>));
```

This renders as `<div data-reactroot="">a<!-- -->bc</div>`. If you try to hydrate this you'll get the error: Text content did not match. Server: "bc" Client: "b".
}
    } else {
      markup = DOMMarkupOperations.createMarkupForProperty(propKey, propValue);
    }
    if (markup) {
      ret += ' ' + markup;
    }
  }
  
  
  if (makeStaticMarkup) {
    return ret;
  }
  if (isRootElement) {
    ret += ' ' + DOMMarkupOperations.createMarkupForRoot();
  }
  return ret;
}
function validateRenderResult(child, type) {
  if (child === undefined) {
    invariant(
      false,
      '%s(...): Nothing was returned from render. This usually means a ' +
        'return statement is missing. Or, to render nothing, ' +
        'return null.',
      getComponentName(type) || 'Component',
    );
  }
}
function resolve(child, context) {