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".
getChildContext() {
          return {text: this.props.text};
        }
        render() {
          return this.props.children;
        }
      }
      Parent.childContextTypes = {text: PropTypes.string};
      PurpleContext = props => <Parent text="purple">{props.children}</Parent>;
      RedContext = props => <Parent text="red">{props.children}</Parent>;
    });
    itRenders('class child with context', async render => {
      class ClassChildWithContext extends React.Component {