Twenty Twelve: Use the correct body class for attachments in the IE stylesheet.

props Marco_Teethgrinder.
see #25506. see [25707].

Built from https://develop.svn.wordpress.org/trunk@25715


git-svn-id: http://core.svn.wordpress.org/trunk@25628 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Thirteen: Remove unneeded .single-attachment selector.

props obenland.
fixes #25506.

Built from https://develop.svn.wordpress.org/trunk@25716


git-svn-id: http://core.svn.wordpress.org/trunk@25629 1a063a9b-81f0-0310-95a4-ce76da25c4cd