Do not export any part of the Promise polyfill
Do not export any part of the Promise polyfill

If we use @export in the Promise polyfill, those methods will end up
attached to the polyfill namespace in the compiled code, and will also
end up in the generated externs (coming soon).

By exporting then() and catch() manually, we avoid this.

Change-Id: Ib12b4d9319452ceed802c8fdc8c47d9c09dd24a5

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