Don't fire 'trackschanged' twice.
Don't fire 'trackschanged' twice.

Closes #783

Change-Id: If355acbe6df94e91fb818f344fff8d9d5d1910ac

russitto/shaka-player,vimond/shaka-player,TheModMaker/shaka-player,russitto/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,TheModMaker/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,indiereign/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,russitto/shaka-player,tvoli/shaka-player,vimond/shaka-player,shaka-project/shaka-player,TheModMaker/shaka-player,vimond/shaka-player,indiereign/shaka-player,TheModMaker/shaka-player,indiereign/shaka-player