After part 1, `JS_HAS_INTL_API` implies `MOZ_ICU4X`, so we can remove some ifdef-guards. Differential Revision: https://phabricator.services.mozilla.com/D245275
After part 1, `JS_HAS_INTL_API` implies `MOZ_ICU4X`, so we can remove some ifdef-guards. Differential Revision: https://phabricator.services.mozilla.com/D245275