Fix requestAnimationFrame timestamps in queue

This resolves #7044 which involved callbacks
in a queue not receiving the same timestamp despite
the specification saying they should. An extra test
was added to verify the correct behavior.

tests/wpt/mozilla/meta/MANIFEST.json

@@ -1016,4 +1016,4 @@
   "rev": null,
   "url_base": "/_mozilla/",
   "version": 2
-}
+}