Twenty Thirteen: fix comment cruft left from r24338.

git-svn-id: http://core.svn.wordpress.org/trunk@24342 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Thirteen: fix up Quote styles for the visual editor, see #24308.

git-svn-id: http://core.svn.wordpress.org/trunk@24343 1a063a9b-81f0-0310-95a4-ce76da25c4cd