MB-12222: more elegant implementation of infinite spinner

Change-Id: I0059519680ba536a373c1294ba42923338d03428
Reviewed-on: http://review.couchbase.org/44390
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>