getRedirectResult method
Returns a UserCredential
from the redirect-based sign in flow.
If sign is successful, returns the signed in user. Or fails with an error
if sign is unsuccessful.
The UserCredential
with a null User is returned if no redirect
operation was called.
Implementation
Future<UserCredential> getRedirectResult() =>
handleThenable(jsObject.getRedirectResult())
.then((u) => UserCredential.fromJsObject(u));