public function getCombinedFilesEnabled()
    {
        if (isset($this->combinedFilesEnabled)) {
            return $this->combinedFilesEnabled;
        }

        // Non-dev sites are always combined
        if (!Director::isDev()) {
            return true;
        }

        // Fallback to default
        return Config::inst()->get(__CLASS__, 'combine_in_dev');
    }