MCE Views can get pummeled by editor-style.css

[wonderboymusic]

editor-style.css loads last, and is less careful with setting * rules that can wipe out font-size and line-height declarations.

Playlists try to stay out of the way and inherit fonts and sizes. However, there probably need to be top level rules for .wp-playlist that ensure proper font-sizing on the front end and in the admin.

Also, have to make sure that the player doesn't inherit the font. Georgia looks gross.

[wonderboymusic]

Initial patch, also cleaning up the borders - they can look gross when the line-height is affected

[wonderboymusic]

In 27865:

Using percentages for playlist font-sizing was ambitious, but fell prey to editor-style.css in the admin. We have switched to using pixels. The editor styles were also forcing MediaElement players to inherit font-family, which was undesirable. And while we're at it, remove the top and bottom border from the playlist's list of tracks, which adds a dash of lovely to the playlist's default styles.

Props nacin for the addition of — in the playlist track list.
Fixes #27600.