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 renderCount = 0;
    var componentB = null;
    var B = React.createClass({
      getInitialState: function() {
        return {updates: 0};
      },
      componentDidMount: function() {
        componentB = this;
      },
      render: function() {
        renderCount++;
        return <div />;
      },
    });
    var A = React.createClass({
      getInitialState: function() {
        return {showB: true};
      },
      render: function() {
        return this.state.showB ? <B /> : <div />;
      },
    });
    var component = ReactTestUtils.renderIntoDocument(<A />);
    ReactUpdates.batchedUpdates(function() {
      
      
      componentB.setState({updates: 1});
      component.setState({showB: false});
    });
    expect(renderCount).toBe(1);