fix(text): Fix VTTCue polyfill in uncompiled mode on Edge
fix(text): Fix VTTCue polyfill in uncompiled mode on Edge

The polyfill assigns a static method over window.VTTCue, which is then
called with "new".  This will not work on Edge in uncompiled mode,
since the method is not an old-style "function".

To fix this, we wrap the chosen static method into a "function".

Change-Id: I9b5687e39b3af1bd160e4db4595de06720564a1d

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