Properly account for text overflow in `.wp-playlist-caption` by adding `display: block`.

Props celloexpressions.
See #27923.



git-svn-id: https://develop.svn.wordpress.org/trunk@28172 602fd350-edb4-49c9-b593-d223f7449a82
Support RTL properly when displaying playlists.

Props SergeyBiryukov.
See #27924.



git-svn-id: https://develop.svn.wordpress.org/trunk@28173 602fd350-edb4-49c9-b593-d223f7449a82