Add test for player unload/load bug.
Add test for player unload/load bug.

This adds a test to reproduce the error described in the Issue #612.
The test is disabled until the bug is fixed.

Change-Id: Idcd9fd2b284b1152b37e43c5058255f3c432c63c

russitto/shaka-player,Ross-cz/shaka-player,TobbeEdgeware/shaka-player,TobbeEdgeware/shaka-player,indiereign/shaka-player,TobbeEdgeware/shaka-player,indiereign/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,vimond/shaka-player,brightcove/shaka-player,vimond/shaka-player,TheModMaker/shaka-player,vimond/shaka-player,tvoli/shaka-player,russitto/shaka-player,Ross-cz/shaka-player,russitto/shaka-player,shaka-project/shaka-player,TheModMaker/shaka-player,tvoli/shaka-player,Ross-cz/shaka-player,tvoli/shaka-player,TheModMaker/shaka-player,brightcove/shaka-player,TheModMaker/shaka-player,brightcove/shaka-player,indiereign/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player