mozilla/bedrock — pull request #860 by sgarrity (2013-05-10 13:30:09+00:00)
Title: Bug 833534 Add missing .visuallyhidden class

Added .visually-hidden() as a LESS mixin that will allow these styles to be added to other classes, but doesn't output anything in the CSS itself. Then there is a .visuallyhidden CSS class in sandstone-resp.less that uses this mixin.