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)

maskedContext,
          ReactPropTypeLocations.context
        );
      }
    }
    return maskedContext;
  },
  /**
   * @param {object} currentContext
   * @return {object}
   * @private
   */
  _processChildContext: function(currentContext) {
    var Component = this._currentElement.type;
    var inst = this._instance;
    if (__DEV__) {
      ReactInstrumentation.debugTool.onBeginProcessingChildContext();
    }
    var childContext = inst.getChildContext && inst.getChildContext();
    if (__DEV__) {
      ReactInstrumentation.debugTool.onEndProcessingChildContext();
    }
    if (childContext) {
      invariant(
        typeof Component.childContextTypes === 'object',
        '%s.getChildContext(): childContextTypes must be defined in order to ' +
        'use getChildContext().',
        this.getName() || 'ReactCompositeComponent'
      );
      if (__DEV__) {