The comment screen hides the author column at narrow screen sizes; this adds back the author info above the comment content.

Merges [26961] to the 3.8 branch.

props SergeyBiryukov.
fixes #26618.

Built from https://develop.svn.wordpress.org/branches/3.8@26962


git-svn-id: http://core.svn.wordpress.org/branches/3.8@26841 1a063a9b-81f0-0310-95a4-ce76da25c4cd