Pass the default mime-type icon as the image for a track when a featured image is not selected for an item in a playlist. Image display in general can be toggled on/off in the modal via Playlist Settings.

Fixes #27525.


Built from https://develop.svn.wordpress.org/trunk@27735


git-svn-id: http://core.svn.wordpress.org/trunk@27572 1a063a9b-81f0-0310-95a4-ce76da25c4cd