The method 'signInWithGoogle' isn't defined for the type 'FirebaseAuth'.
Future<FirebaseUser> _handleSignIn() async {
GoogleSignInAccount googleUser = await _googleSignIn.signIn();
GoogleSignInAuthentication googleAuth = await googleUser.authentication;
final AuthCredential credential = GoogleAuthProvider.getCredential(
accessToken: googleAuth.accessToken,
idToken: googleAuth.idToken,
);
final AuthResult authResult = await _auth.signInWithCredential(credential);
FirebaseUser user = authResult.user;
print("signed in " + user.displayName);
return user;
}