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.
getChildContext() {
          return {text2: 'red'};
        }
        render() {
          return <Grandchild />;
        }
      }
      Child.childContextTypes = {text2: PropTypes.string};
      const Grandchild = (props, context) => {
        return (
          <div>
            <div id="first">{context.text1}</div>
            <div id="second">{context.text2}</div>
          </div>
        );
      };
      Grandchild.contextTypes = {
        text1: PropTypes.string,
        text2: PropTypes.string,
      };
      const e = await render(<Parent />);
      expect(e.querySelector('#first').textContent).toBe('purple');
      expect(e.querySelector('#second').textContent).toBe('red');
    });
    itRenders(
      'with a call to componentWillMount before getChildContext',
      async render => {
        class WillMountContext extends React.Component {