test: Improved UA parser with Chromecast support

Our Chromecast tests have started reporting the device as "Linux
aarch64", which is not useful.  This moves us to a fork of
ua-parser-js which can recognize a Chromecast and report its firmware
version.  A pull request has been submitted at
faisalman/ua-parser-js#439.

Change-Id: I158cc2b0dd6fb6ec03825ac9648b05a3096da31b

package.json

@@ -55,6 +55,7 @@
     "stylelint": "github:theodab/stylelint",
     "stylelint-config-standard": "^18.3.0",
     "tippy.js": "^4.3.1",
+    "ua-parser-js": "github:joeyparrish/ua-parser-js#develop",
     "which": "^1.3.1"
   },
   "main": "dist/shaka-player.compiled.js",