Use Uint8ArrayUtils.concat in polyfill.
Use Uint8ArrayUtils.concat in polyfill.

Change-Id: Ie6170e662ba8964fd2d683f2d06f54b38326e91c

tvoli/shaka-player,tvoli/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,shaka-project/shaka-player