It's commented out, but if the gzip option is uncommented there's a bug in it. It's missing the '/' separator between the output directory and the file name.
$fp = gzopen($this->_archive_dir . $this->_archive_name . '.gz', 'w9');
Should be
$fp = gzopen($this->_archive_dir . '/' . $this->_archive_name . '.gz', 'w9');
And why are jquery and and sha256.js not included into the combined scripts but loaded separately?