Eliminate the transition animation on the responsive sidebar; set the responsive sidebar to display: none by default so it doesn't appear momentarily when loading the page. Fixes #25969.


Built from https://develop.svn.wordpress.org/trunk@26414


git-svn-id: http://core.svn.wordpress.org/trunk@26314 1a063a9b-81f0-0310-95a4-ce76da25c4cd