Fix start-of-day handling of cookieName.

@@ -156,7 +156,7 @@ define(function(require) {
                 }
                 var sessionId = self.get('sessionId');
                 if (sessionId) {
-                    $.cookie('cookieName', sessionId);
+                    $.cookie(cookieName, sessionId);
                 } else {
                     self.set('sessionId', $.cookie(cookieName));
                 }