Flutter - access BLoC from pushed page using nested Navigator

bloc_and_navigation.dart

class BasicNavigator extends Navigator {
  BasicNavigator({Key key, @required WidgetBuilder rootBuilder})
      : super(
          key: key,
          onGenerateRoute: (RouteSettings settings) {
            return PageRouteBuilder(
              pageBuilder: (BuildContext context, _, __) {
                return rootBuilder(context);
              },
            );
          },
        );
}

class PopNavigator extends StatelessWidget {
  final _navigatorKey = GlobalKey<NavigatorState>();

  final WidgetBuilder rootBuilder;

  PopNavigator({Key key, @required this.rootBuilder}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return WillPopScope(
      child: BasicNavigator(
        key: _navigatorKey,
        rootBuilder: rootBuilder,
      ),
      onWillPop: () async {
        return !await _navigatorKey.currentState.maybePop();
      },
    );
  }
}

class RootPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocProvider(
      bloc: _myBloc, // any BLoC that can be used in FirstPage / SecondPage
      child: PopNavigator(
        rootBuilder (_) => FirstPage(),
      ),
    );
  }
}

class FirstPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('First page'),
      ),
      body: Center(
        child: Column(
          children: <Widget>[
            BlocBuilder(
              bloc: BlocProvider.of<MyBloc>(context),
              builder: (context, state) {
                return Text(state.data);
              },
            ),
            RaisedButton(
              child: Text('Open second page'),
              onPressed: () {
                Navigator.of(context).push(
                  MaterialPageRoute(
                    builder: (_) => SecondPage(),
                  ),
                );
              },
            ),
          ],
        ),
      ),
    );
  }
}

class SecondPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Second page'),
      ),
      body: Center(
        child: Column(
          children: <Widget>[
            BlocBuilder(
              bloc: BlocProvider.of<MyBloc>(context),
              builder: (context, state) {
                return Text(state.data);
              },
            ),
            RaisedButton(
              child: Text('Back to first page'),
              onPressed: () {
                Navigator.of(context).pop();
              },
            ),
          ],
        ),
      ),
    );
  }
}