message: fix: window defensiveness with promise handler
diff: @@ -431,7 +431,7 @@ Raven.prototype = {
  */
  _attachPromiseRejectionHandler: function() {
  this._promiseRejectionHandler = this._promiseRejectionHandler.bind(this);
  - _window.addEventListener('unhandledrejection', this._promiseRejectionHandler);
  + _window.addEventListener && _window.addEventListener('unhandledrejection', this._promiseRejectionHandler);
  return this;
  },
  @@ -441,7 +441,7 @@ Raven.prototype = {
  * @return {raven}
  */
  _detachPromiseRejectionHandler: function() {
  - _window.removeEventListener('unhandledrejection', this._promiseRejectionHandler);
  + _window.removeEventListener && _window.removeEventListener('unhandledrejection', this._promiseRejectionHandler);
  return this;
  },
  