Use visibility hidden on remarkup checkboxes

Summary: Fixes T12850, marks it hidden with zero width so the element still exists in the DOM

Test Plan: T12850 code, locally

Reviewers: epriestley, amckinley, avivey

Reviewed By: avivey

Subscribers: Korvin

Maniphest Tasks: T12850

Differential Revision: https://secure.phabricator.com/D18130