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".
itRenders('an input with a value and readOnly', async render => {
        const e = await render(<input value="foo" readOnly={true} />);
        expect(e.value).toBe('foo');
      });
      itRenders(
        'an input with a value and no onChange/readOnly',
        async render => {
          
          
          const e = await render(<input value="foo" />, 1);
          expect(e.value).toBe('foo');
          expect(e.getAttribute('value')).toBe('foo');
        },
      );
      itRenders('an input with a defaultValue', async render => {
        const e = await render(<input defaultValue="foo" />);
        expect(e.value).toBe('foo');
        expect(e.getAttribute('value')).toBe('foo');
        expect(e.getAttribute('defaultValue')).toBe(null);
      });
      itRenders('an input value overriding defaultValue', async render => {
        const e = await render(
          <input value="foo" defaultValue="bar" readOnly={true} />,
          1,
        );
        expect(e.value).toBe('foo');
        expect(e.getAttribute('value')).toBe('foo');
        expect(e.getAttribute('defaultValue')).toBe(null);
      });
      itRenders(