Fix bug in manifest parser helpers.
Fix bug in manifest parser helpers.

Change-Id: I506ebff70443a094a5e7d95f6b3cddf5d76eb5bd

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