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)

this._checkPropTypes(
          Component.childContextTypes,
          childContext,
          ReactPropTypeLocations.childContext
        );
      }
      for (var name in childContext) {
        invariant(
          name in Component.childContextTypes,
          '%s.getChildContext(): key "%s" is not defined in childContextTypes.',
          this.getName() || 'ReactCompositeComponent',
          name
        );
      }
      return Object.assign({}, currentContext, childContext);
    }
    return currentContext;
  },
  /**
   * Processes props by setting default values for unspecified props and
   * asserting that the props are valid. Does not mutate its argument; returns
   * a new props object with defaults merged in.
   *
   * @param {object} newProps
   * @return {object}
   * @private
   */
  _processProps: function(newProps) {
    if (__DEV__) {
      var Component = this._currentElement.type;