How to configure go back button in Browser for Flutter Web App

onWillPop: () {
  Navigator.pop(context);
  return new Future(() => true);
}

In case if you don't want to navigate to a new page

    @override
  Widget build(BuildContext context) {
    return WillPopScope(
      onWillPop: () async => true,
      child: Scaffold(

        key: _scaffold,
        backgroundColor: Colors.indigo,
        body: Center(
          child: Container(
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                registerForm(),
                registerBtn(),
                SizedBox(height: 30,),
                _buildSignInButton()
              ],
            ),
          ),
        ),
      ),
    );
  }

onWillPop Navigate to a new Page

class webScope extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new WillPopScope(
      onWillPop: () async => Navigator.push(context, MaterialPageRoute(builder: (context) => new NewPageWidget())),
      child: Scaffold(
        appBar: new AppBar(
          title: new Text("webScope"),
        ),
      ),
    );
  }
}