Run the [`fixtures/ssr` test harness](https://github.com/facebook/react/tree/master/fixtures/ssr). In the terminal, the following warning is logged:

```
Warning: Unknown prop `onClick` on <a> tag. Remove this prop from the element. For details, see https://fb.me/react-unknown-prop
  in a (at Page.js:12)
  in p (at Page.js:18)
  in div (at Page.js:17)
  in Page (at App.js:12)
  in div (at App.js:10)
  in body (at Chrome.js:17)
  in html (at Chrome.js:9)
  in Chrome (at App.js:9)
  in App (at render.js:18)
```

SSR behavior should match client-side behavior and not warn for a valid attribute.
render() {
          return <div ref="myDiv" />;
        }
      }
      const markup = ReactDOMServer.renderToString(<RefsComponent />);
      const root = document.createElement('div');
      root.innerHTML = markup;
      let component = null;
      resetModules();
      await asyncReactDOMRender(
        <RefsComponent ref={e => (component = e)} />,
        root,
      );
      expect(component.refs.myDiv).toBe(root.firstChild);
    });
  });
  describe('reconnecting to server markup', function() {
    var EmptyComponent;
    beforeEach(() => {
      EmptyComponent = class extends React.Component {
        render() {