Fix use of ES6 String.prototype.includes
Fix use of ES6 String.prototype.includes

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Change-Id: I2d84da0c00e115a2b44824b5264a9236f5fbdc8d

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