Enabling offline mode doesn't skip tracks that haven't been downloaded

[isch]

Version: 8.4.42.722 armV7

To reproduce:

- Create a playlist

- Add a saved track to it that is on a playlist which is already downloaded

- Add a track to it that is not already downloaded

- Enable offline mode

- View the playlist and see the second track is greyed out

- Play the first track

- Open the queue, see the second track will be played next

- Wait for the first track to play, and observe the second track actually play

Alternative ways to reproduce:

- Go to an album

- Add the first track to a playlist and download the playlist

- Enable offline mode

- Go back to the album and see t hat only the first track is not greyed out.

- Play the first track

- Open the queue, see all other tracks from the album are in the queue

- Wait for the first track to play, and observe the second track actually play