Tie worker rights to cookie policy like Chromium does

Instead of always allowing all workers, disallow when similar cookies
would have been disallowed.

This is following the same logic as Chromium is using.

Change-Id: I6b9d6c63b894287f64171b138fe03ec080af5115
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Peter Varga <pvarga@inf.u-szeged.hu>