message: Removed black background if activity stack
  Keeps it backward compatible and only want black background for fragment navigation to keep consistent with Android activity navigation background
diff: @@ -84,7 +84,7 @@ class NavigationStack extends React.Component<NavigationStackProps, NavigationSt
  keys={keys}
  fragment={fragment}
  finish={finish}
  - style={styles.stack}
  + style={[styles.stack, fragment ? {backgroundColor: '#000'} : null]}
  {...this.getAnimation()}
  onDidNavigateBack={this.onDidNavigateBack}>
  <BackButton onPress={this.handleBack} />
  @@ -114,7 +114,6 @@ var NVNavigationStack = requireNativeComponent<any>('NVNavigationStack', null);
  const styles = StyleSheet.create({
  stack: {
  flex: 1,
  - backgroundColor: '#000',
  },
  });
  