Summary: Let's see if I did this right. This adds on and off state icons (1 and 2x) for conpherence. I think I need to tweak and add more CSS to have the off hover state be the on icon. Will check.
Test Plan: spritegen
Reviewers: epriestley, btrahan
Reviewed By: epriestley
CC: aran, Korvin
Maniphest Tasks: T2400
Differential Revision: https://secure.phabricator.com/D4709
