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.getAttribute('htmlFor')).toBe('test');
      });
      itRenders('for attribute on custom elements', async render => {
        const e = await render(<div is="custom-element" for="test" />);
        expect(e.getAttribute('for')).toBe('test');
      });
    });
    describe('numeric properties', function() {
      itRenders(
        'positive numeric property with positive value',
        async render => {
          const e = await render(<input size={2} />);
          expect(e.getAttribute('size')).toBe('2');
        },
      );
      itRenders(
        'no positive numeric property with zero value',
        async render => {
          const e = await render(<input size={0} />);
          expect(e.hasAttribute('size')).toBe(false);
        },
      );
      itRenders('numeric property with zero value', async render => {
        const e = await render(<ol start={0} />);
        expect(e.getAttribute('start')).toBe('0');
      });
    });
    describe('props with special meaning in React', function() {
      itRenders('no ref attribute', async render => {
        class RefComponent extends React.Component {