Hide Search text better
Summary: Previously, this text was transparent, moved it to a new span and set visibility on it.
Test Plan: review search in FF, Chrome. Text no longer displays.
Reviewers: btrahan, epriestley
Reviewed By: epriestley
Subscribers: Korvin, epriestley
Maniphest Tasks: T7710
Differential Revision: https://secure.phabricator.com/D12219