feat(MediaCap): Add MediaCap polyfill to uncompiled.js

Adding MediaCapabilities polyfill to uncompiled.js, so that the
polyfill can be used in unit tests.

Fixed the tests failure in Tizen, Safari and other browsers.

Issue shaka-project#1391

Change-Id: Ia9e220d00ac48bf4a024fb780e4f20e9e111ecc7

shaka-player.uncompiled.js

@@ -37,6 +37,7 @@ goog.require('shaka.polyfill.Fullscreen');
 goog.require('shaka.polyfill.InputEvent');
 goog.require('shaka.polyfill.MathRound');
 goog.require('shaka.polyfill.MediaSource');
+goog.require('shaka.polyfill.MediaCapabilities');
 goog.require('shaka.polyfill.Orientation');
 goog.require('shaka.polyfill.PatchedMediaKeysApple');
 goog.require('shaka.polyfill.PatchedMediaKeysMs');