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.
super();
            this.state = {value: 'Hello'};
          }
          handleChange(event) {
            if (this.props.onChange) {
              this.props.onChange(event);
            }
            this.setState({value: event.target.value});
          }
          render() {
            return (
              <textarea
                value={this.state.value}
                onChange={this.handleChange.bind(this)}
              />
            );
          }
        };
        ControlledCheckbox = class extends React.Component {
          constructor() {
            super();
            this.state = {value: true};
          }
          handleChange(event) {