message: Disabled other navigator history manager
  Preferred this to checking platform because it works for, e.g., stack in modal. Might want to keep a stack in modal and not have to pass 'none' to all the navigations in it to prevent it participating in history
diff: @@ -10,7 +10,8 @@ var stateNavigator = createStateNavigator();
  const notificationsNavigator = new StateNavigator(stateNavigator);
  stateNavigator.navigate('home');
  - if (Platform.OS !== 'web')
  + notificationsNavigator.historyManager.disabled = true;
  + notificationsNavigator.historyManager.stop();
  notificationsNavigator.navigate('notifications');
  const Stack = ({navigator}) => (
  