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 ReactUpdates;
describe('ReactUpdates', function() {
  beforeEach(function() {
    React = require('React');
    ReactDOM = require('ReactDOM');
    ReactTestUtils = require('ReactTestUtils');
    ReactUpdates = require('ReactUpdates');
  });
  it('should batch state when updating state twice', function() {
    var updateCount = 0;
    var Component = React.createClass({
      getInitialState: function() {
        return {x: 0};
      },
      componentDidUpdate: function() {
        updateCount++;
      },
      render: function() {
        return <div>{this.state.x}</div>;
      },
    });
    var instance = ReactTestUtils.renderIntoDocument(<Component />);
    expect(instance.state.x).toBe(0);
    ReactUpdates.batchedUpdates(function() {
      instance.setState({x: 1});
      instance.setState({x: 2});
      expect(instance.state.x).toBe(0);
      expect(updateCount).toBe(0);
    });
    expect(instance.state.x).toBe(2);