call offAuth() with correct method.

closes #471.

Author: jamestalmage

src/FirebaseAuth.js

@@ -155,37 +155,35 @@
     },
 
     // Helper onAuth() callback method for the two router-related methods.
-    _routerMethodOnAuthCallback: function(deferred, rejectIfAuthDataIsNull, authData) {
-      if (authData !== null) {
-        deferred.resolve(authData);
-      } else if (rejectIfAuthDataIsNull) {
-        deferred.reject("AUTH_REQUIRED");
-      } else {
-        deferred.resolve(null);
-      }
+    _routerMethodOnAuthPromise: function(rejectIfAuthDataIsNull) {
+      var ref = this._ref,
+          deferred = this._q.defer();
+
+      var callback = function (authData){
+        if (authData !== null) {
+          deferred.resolve(authData);
+        } else if (rejectIfAuthDataIsNull) {
+          deferred.reject("AUTH_REQUIRED");
+        } else {
+          deferred.resolve(null);
+        }
+        // Turn off this onAuth() callback since we just needed to get the authentication data once.
+        ref.offAuth(callback);
+      };
 
-      // Turn off this onAuth() callback since we just needed to get the authentication data once.
-      this._ref.offAuth(this._routerMethodOnAuthCallback);
+      return deferred.promise;
     },
 
     // Returns a promise which is resolved if the client is authenticated and rejects otherwise.
     // This can be used to require that a route has a logged in user.
     requireAuth: function() {
-      var deferred = this._q.defer();
-
-      this._ref.onAuth(this._routerMethodOnAuthCallback.bind(this, deferred, /* rejectIfAuthDataIsNull */ true));
-
-      return deferred.promise;
+      return this._routerMethodOnAuthPromise(true);
     },
 
     // Returns a promise which is resolved with the client's current authenticated data. This can
     // be used in a route's resolve() method to grab the current authentication data.
     waitForAuth: function() {
-      var deferred = this._q.defer();
-
-      this._ref.onAuth(this._routerMethodOnAuthCallback.bind(this, deferred, /* rejectIfAuthDataIsNull */ false));
-
-      return deferred.promise;
+      return this._routerMethodOnAuthPromise(false);
     },