title: How can I perform firebase authentication with facebook in flutter
body: <p>I'm trying to add firebase and facebook authentication in my app. Facebook auth is already done:</p>
  
  <pre><code>final facebookLogin = FacebookLogin();
  final result = await facebookLogin.logInWithReadPermissions(['email']);
  
  switch (result.status) {
    case FacebookLoginStatus.loggedIn:
      final token = result.accessToken.token;
      final graphResponse = await http.get(
          'https://graph.facebook.com/v2.12/me?fields=name,first_name,last_name,email&amp;access_token=$token');
      Map&lt;String, dynamic&gt; user = jsonDecode(graphResponse.body);
      // _onGetFacebookUser(user);
  </code></pre>
  
  <p>I don't know how to perform firebase authentication with facebook result.</p>
  
  <p>I've already watched <a href="https://stackoverflow.com/a/50712363/11321310">this answer</a>, but it doesn't help, there is only facebook login code example.
  I've found <a href="https://medium.com/flutterpub/firebase-fb-sign-in-and-flutter-7ab4bdc7172e" rel="nofollow noreferrer">this article</a>, but there is no method <code>signInWithFacebook</code></p>