R1:70e0deb368e7

Empty list filters won't display if empty

Summary: Exactly what it says on the tin

Test Plan: No shadow when visiting saved custom queries in Maniphest. Still appears normally for other use sites

Reviewers: epriestley, chad

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5535