Expanded the fullscreen polyfill.
Expanded the fullscreen polyfill.

Now it includes fullscreenEnabled.

Closes #669

Change-Id: I7df3c422ecc72215a48ba72ac57aae2bc9b600d5

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