/usr/share/xul-ext/self-destructing-cookies/lib/ is in xul-ext-self-destructing-cookies 0.4.12-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/xul-ext/self-destructing-cookies/lib/cookietracker.js
/usr/share/xul-ext/self-destructing-cookies/lib/domaintree.js
/usr/share/xul-ext/self-destructing-cookies/lib/domstorage.js
/usr/share/xul-ext/self-destructing-cookies/lib/gui-android.js
/usr/share/xul-ext/self-destructing-cookies/lib/gui-australis.js
/usr/share/xul-ext/self-destructing-cookies/lib/gui-desktop.js
/usr/share/xul-ext/self-destructing-cookies/lib/history.js
/usr/share/xul-ext/self-destructing-cookies/lib/main.js
/usr/share/xul-ext/self-destructing-cookies/lib/src-pagemod.js
/usr/share/xul-ext/self-destructing-cookies/lib/src-simpletab.js
/usr/share/xul-ext/self-destructing-cookies/lib/src-smarttab.js
/usr/share/xul-ext/self-destructing-cookies/lib/undelete.js