in firefox, go to about:config
type 'intl.accept_languages' into the filter
double click (or rightclick->modify) the intl.accept_languages entry
press ok and it will automatically convert chrome://global/locale/intl.properties into the actual language properties
in firefox, go to about:config languages' into the filter languages entry //global/ locale/ intl.properties into the actual language properties
type 'intl.accept_
double click (or rightclick->modify) the intl.accept_
press ok and it will automatically convert chrome: