Twenty Thirteen: avoid galleries not being displayed on single in IE8, props obenland. See #23996.

git-svn-id: https://core.svn.wordpress.org/trunk@23943 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Thirteen: remove overly-specific post meta styles, props ziegenberg and obenland. Fixes #23962.

git-svn-id: https://core.svn.wordpress.org/trunk@23944 1a063a9b-81f0-0310-95a4-ce76da25c4cd