Fix specifications of some "Visual Only" elements

Summary: See PHI823. These got "visual-only" but should acutally get "aural => false" to pick up "aria-hidden".

Test Plan: Viewed page source, saw both "visual-only" and "aria-hidden".

Reviewers: amckinley

Reviewed By: amckinley

Differential Revision: https://secure.phabricator.com/D20157