Add test to assert that media elements w/o valid sources do not bump the link count
Add test to assert that media elements w/o valid sources do not bump the link count

Note: Media elements w/o valid source DO bump the media element count
(video_count/audio_count).

der-lyse/newsboat,der-lyse/newsboat,newsboat/newsboat,der-lyse/newsboat,newsboat/newsboat,der-lyse/newsboat,newsboat/newsboat,der-lyse/newsboat,newsboat/newsboat,newsboat/newsboat,newsboat/newsboat,der-lyse/newsboat,der-lyse/newsboat,der-lyse/newsboat,newsboat/newsboat,newsboat/newsboat