Hello,

After updating to React 15.0.1, we are getting the following error:

```
Uncaught TypeError: Cannot read property 'addEventListener' of null
```

![image](https://cloud.githubusercontent.com/assets/4996164/14602577/5bb4e9f2-0571-11e6-9aa1-98de49f50d76.png)

var updateCount = 0;
    var Component = React.createClass({
      getInitialState: function() {
        return {y: 0};
      },
      componentDidUpdate: function() {
        updateCount++;
      },
      render: function() {
        return <div>({this.props.x}, {this.state.y})</div>;
      },
    });
    var container = document.createElement('div');
    var instance = ReactDOM.render(<Component x={0} />, container);
    expect(instance.props.x).toBe(0);
    expect(instance.state.y).toBe(0);
    ReactUpdates.batchedUpdates(function() {
      ReactDOM.render(<Component x={1} />, container);
      instance.setState({y: 2});
      expect(instance.props.x).toBe(0);
      expect(instance.state.y).toBe(0);
      expect(updateCount).toBe(0);
    });
    expect(instance.props.x).toBe(1);
    expect(instance.state.y).toBe(2);
    expect(updateCount).toBe(1);
  });
  it('should batch parent/child state updates together', function() {
    var parentUpdateCount = 0;
    var Parent = React.createClass({