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".
expect(e.childNodes.length).toBe(0);
      });
      itRenders('false single child as blank', async render => {
        const e = await render(<div>{false}</div>);
        expect(e.childNodes.length).toBe(0);
      });
      itRenders('undefined single child as blank', async render => {
        const e = await render(<div>{undefined}</div>);
        expect(e.childNodes.length).toBe(0);
      });
      itRenders('a null component children as empty', async render => {
        const NullComponent = () => null;
        const e = await render(<div><NullComponent /></div>);
        expect(e.childNodes.length).toBe(0);
      });
      itRenders('null children as blank', async render => {
        const e = await render(<div>{null}foo</div>);
        expect(e.childNodes.length).toBe(1);
        expectTextNode(e.childNodes[0], 'foo');
      });
      itRenders('false children as blank', async render => {
        const e = await render(<div>{false}foo</div>);
        expect(e.childNodes.length).toBe(1);
        expectTextNode(e.childNodes[0], 'foo');
      });
      itRenders('null and false children together as blank', async render => {
        const e = await render(<div>{false}{null}foo{null}{false}</div>);
        expect(e.childNodes.length).toBe(1);
        expectTextNode(e.childNodes[0], 'foo');
      });