message: Kept system item in synch with tab
  Otherwise it kept the old system item if the new system item prop was empty. Because new prop = old prop (both empty) but tab has a system item
diff: @@ -104,12 +104,6 @@ using namespace facebook::react;
  ->onPress(NVTabBarItemEventEmitter::OnPress{});
  }
  -- (void)prepareForRecycle
  -{
  - [super prepareForRecycle];
  - _oldSystemItemVal = @"";
  -}
  -
  #pragma mark - RCTComponentViewProtocol
  - (void)mountChildComponentView:(UIView<RCTComponentViewProtocol> *)childComponentView index:(NSInteger)index
  