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

Props celloexpressions.
See #27923.


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git-svn-id: http://core.svn.wordpress.org/trunk@28003 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/js/mediaelement/wp-mediaelement.css

@@ -98,6 +98,7 @@
 }
 
 .wp-playlist-caption {
+	display: block;
 	max-width: 88%;
 	overflow: hidden;
 	text-overflow: ellipsis;