Given the following test case

``` jsx
function TestCmp() {
  return <span>{NaN}</span>;
}

ReactDOM.render(<TestCmp />, document.getElementById('app'));
```

Produces the following warning:

```
Warning: Component's children should not be mutated.
    in span (created by TestCmp)
    in TestCmp (created by Unknown)
```

This is probably caused by [this mutation check](https://github.com/facebook/react/blob/328fc75bc910032ff37dc9d93429fb14b476bd0d/src/renderers/shared/hooks/ReactChildrenMutationWarningHook.js#L34), which was introduced in 15.3.0, but it doesn't work for NaN, because NaN != NaN

var lifecycle = [];
        class TestComponent extends React.Component {
          constructor(props) {
            super(props);
            lifecycle.push('getInitialState');
            this.state = {name: 'TestComponent'};
          }
          componentWillMount() {
            lifecycle.push('componentWillMount');
          }
          componentDidMount() {
            lifecycle.push('componentDidMount');
          }
          render() {
            lifecycle.push('render');
            return <span>Component name: {this.state.name}</span>;
          }
          componentWillUpdate() {
            lifecycle.push('componentWillUpdate');
          }
          componentDidUpdate() {
            lifecycle.push('componentDidUpdate');
          }
          shouldComponentUpdate() {
            lifecycle.push('shouldComponentUpdate');
          }
          componentWillReceiveProps() {
            lifecycle.push('componentWillReceiveProps');
          }
          componentWillUnmount() {