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

});
    it('should generate simple markup for attribute with `>` symbol', () => {
      var response = ReactServerRendering.renderToString(
        <img data-attr=">" />
      );
      expect(response).toMatch(new RegExp(
        '<img data-attr="&gt;" ' + ROOT_ATTRIBUTE_NAME + '="" ' +
          ID_ATTRIBUTE_NAME + '="[^"]+" ' +
          ReactMarkupChecksum.CHECKSUM_ATTR_NAME + '="[^"]+"/>'
      ));
    });
    it('should generate comment markup for component returns null', () => {
      class NullComponent extends React.Component {
        render() {
          return null;
        }
      }
      var response = ReactServerRendering.renderToString(<NullComponent />);
      expect(response).toBe('<!-- react-empty: 1 -->');
    });
    it('should not register event listeners', () => {
      var EventPluginHub = require('EventPluginHub');
      var cb = jest.fn();
      ReactServerRendering.renderToString(
        <span onClick={cb}>hello world</span>
      );
      expect(EventPluginHub.__getListenerBank()).toEqual({});
    });
    it('should render composite components', () => {
      class Parent extends React.Component {