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

'in `undefined` being returned. If you need to access the same ' +
        'value within the child component, you should pass it as a different ' +
        'prop. (https://fb.me/react-special-props)',
        displayName
      );
    }
  };
  warnAboutAccessingRef.isReactWarning = true;
  Object.defineProperty(props, 'ref', {
    get: warnAboutAccessingRef,
    configurable: true,
  });
}
/**
 * Factory method to create a new React element. This no longer adheres to
 * the class pattern, so do not use new to call it. Also, no instanceof check
 * will work. Instead test $$typeof field against Symbol.for('react.element') to check
 * if something is a React Element.
 *
 * @param {*} type
 * @param {*} key
 * @param {string|object} ref
 * @param {*} self A *temporary* helper to detect places where `this` is
 * different from the `owner` when React.createElement is called, so that we
 * can warn. We want to get rid of owner and replace string `ref`s with arrow
 * functions, and as long as `this` and owner are the same, there will be no
 * change in behavior.
 * @param {*} source An annotation object (added by a transpiler or otherwise)
 * indicating filename, line number, and/or other information.
 * @param {*} owner