/usr/share/xul-ext/ is in xul-ext-firexpath 0.9.7-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/xul-ext/firexpath/
/usr/share/xul-ext/firexpath/chrome.manifest
/usr/share/xul-ext/firexpath/content/
/usr/share/xul-ext/firexpath/content/FirePath.png
/usr/share/xul-ext/firexpath/content/FirePathPanel.js
/usr/share/xul-ext/firexpath/content/bindings.xml
/usr/share/xul-ext/firexpath/content/firebugOverlay.xul
/usr/share/xul-ext/firexpath/content/sizzle.js
/usr/share/xul-ext/firexpath/defaults/
/usr/share/xul-ext/firexpath/defaults/preferences/
/usr/share/xul-ext/firexpath/defaults/preferences/000system.js
/usr/share/xul-ext/firexpath/defaults/preferences/FirePathPref.js
/usr/share/xul-ext/firexpath/install.rdf
/usr/share/xul-ext/firexpath/locale/
/usr/share/xul-ext/firexpath/locale/en-US/
/usr/share/xul-ext/firexpath/locale/en-US/FirePath.dtd
/usr/share/xul-ext/firexpath/locale/en-US/FirePath.properties
/usr/share/xul-ext/firexpath/skin/
/usr/share/xul-ext/firexpath/skin/classic/
/usr/share/xul-ext/firexpath/skin/classic/FirePath.css
/usr/share/xul-ext/firexpath/skin/classic/FirePathPanel.css