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".
<ES6ClassComponent id="foobarbaz" />,
          ));
        it('should reconnect Pure Component to Pure Component', () =>
          expectMarkupMatch(
            <PureComponent id="foobarbaz" />,
            <PureComponent id="foobarbaz" />,
          ));
        it('should reconnect Bare Element to Pure Component', () =>
          expectMarkupMatch(<PureComponent id="foobarbaz" />, bareElement));
        it('should reconnect ES6 Class to Bare Element', () =>
          expectMarkupMatch(bareElement, <ES6ClassComponent id="foobarbaz" />));
        it('should reconnect Pure Component to Bare Element', () =>
          expectMarkupMatch(bareElement, <PureComponent id="foobarbaz" />));
        it('should reconnect Bare Element to Bare Element', () =>
          expectMarkupMatch(bareElement, bareElement));
      });
      it('should error reconnecting different element types', () =>
        expectMarkupMismatch(<div />, <span />));
      it('should error reconnecting missing attributes', () =>
        expectMarkupMismatch(<div id="foo" />, <div />));
      it('should error reconnecting added attributes', () =>
        expectMarkupMismatch(<div />, <div id="foo" />));
      it('should error reconnecting different attribute values', () =>
        expectMarkupMismatch(<div id="foo" />, <div id="bar" />));
    });
    describe('inline styles', function() {
      it('should error reconnecting missing style attribute', () =>
        expectMarkupMismatch(<div style={{width: '1px'}} />, <div />));
      it('should error reconnecting added style attribute', () =>
        expectMarkupMismatch(<div />, <div style={{width: '1px'}} />));