/usr/lib/ is in firefox-locale-uk 28.0+build2-0ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/firefox/
/usr/lib/firefox/distribution/
/usr/lib/firefox/distribution/searchplugins/
/usr/lib/firefox/distribution/searchplugins/locale/
/usr/lib/firefox/distribution/searchplugins/locale/uk/
/usr/lib/firefox/distribution/searchplugins/locale/uk/metamarket.xml
/usr/lib/firefox/distribution/searchplugins/locale/uk/google.xml
/usr/lib/firefox/distribution/searchplugins/locale/uk/meta-ua.xml
/usr/lib/firefox/distribution/searchplugins/locale/uk/yandex.xml
/usr/lib/firefox/distribution/searchplugins/locale/uk/duckduckgo.xml
/usr/lib/firefox/distribution/searchplugins/locale/uk/wikipedia-uk.xml
/usr/lib/firefox-addons/
/usr/lib/firefox-addons/extensions/
/usr/lib/firefox-addons/extensions/langpack-uk@firefox.mozilla.org.xpi