Merge pull request FirebaseExtended#433 from firebase/jw-logout-bug

Fixed bug from calling $logout() multiple times

src/firebaseSimpleLogin.js

@@ -97,9 +97,10 @@
       // Tell the simple login client to log us out.
       this._authClient.logout();
 
-      // Forget who we were, so that any getCurrentUser calls will wait for
-      // another user event.
-      delete this._currentUserData;
+      // Forget who we were immediately, so that any getCurrentUser() calls
+      // will resolve the user as logged out even before the _onLoginEvent()
+      // fires and resets this._currentUserData to null again.
+      this._currentUserData = null;
     },
 
     // Creates a user for Firebase Simple Login. Function 'cb' receives an
@@ -231,4 +232,4 @@
       }
     }
   };
-})();
+})();