message: Incremented event count only if firing event
  Otherwise native and js get out of step
diff: - (void)setCurrentTab:(NSInteger)index
  {
  - _nativeEventCount++;
  if (index != _selectedIndex && _selectedIndex != NSNotFound) {
  + _nativeEventCount++;
  self.onTabSelected(@{
  @"tab": @(index),
  @"eventCount": @(_nativeEventCount),
  