title: Will currentUser() return an anonymous user Firebase?
body: <p>I cannot seem to find this answer anywhere. When randomly authenticating a user with <code>base.auth().signInAnonymously()</code>, and then calling <code>currentUser()</code>, will it return that anonymous user? </p>
  
  <p>Basically, I am trying to figure out if a user is actually logged in, or if they are anonymously authenticated. Please help.</p>