message: Kepts subview visible during pop
  If the real subview is added then when it's removed during a javascript back navigation the screen goes white when it's popped. Think it's because it's removed from the superview. Adding a placeholder ensures the real superview is retained in teh pop
diff: - (void)insertReactSubview:(UIView *)subview atIndex:(NSInteger)atIndex
  {
  - [super insertReactSubview:subview atIndex:atIndex];
  + [super insertReactSubview:[UIView new] atIndex:atIndex];
  UIViewController *viewController = [UIViewController new];
  [viewController.view insertSubview:subview atIndex:0];
  [_navigationController pushViewController:viewController animated:YES];
  