title: Firebase's AngularFire Authentication $onAuth throwing "Undefined is not a function"
body: <p>I'm trying to upgrade an application to the new Firebase Authentication methods. I've got most things working, but for some reason when I try this.</p>
  
  <pre><code>myApp.controller('StatusController', function(
    $scope, $rootScope,
      $location, $firebase, $firebaseAuth, FIREBASE_URL) {
  
    $scope.logout = function() {
      Authentication.logout();
      $location.path('/login');
    } //logout
  
    $rootScope.$onAuth(function(authUser) {
      var ref = new Firebase(FIREBASE_URL + '/users/' + authUser.uid);
      var user = $firebase(ref).$asObject();
  
      user.$loaded().then(function() {
        $rootScope.currentUser = user;
      });
    }); //login
  
    $rootScope.$on('logout', function(e, authUser) {
      $rootScope.currentUser = null;
    }); //login
  
  }); //StatusController
  </code></pre>
  
  <p>I'm getting a "undefined is not a function", even when I just try the example on the site. I'm not sure why this is happening. Just for reference, this controller keeps track of the authentication in order to update the site navigation.</p>
  
  <pre><code>&lt;header&gt;
    &lt;nav class="cf" ng-include="'views/nav.html'"
      ng-controller="StatusController"&gt;&lt;/nav&gt;
  &lt;/header&gt;
  </code></pre>