Support mixed `if-domain` / `unless-domain` for network rules

[ameshkov]

trafficstars

For now there's no way it can be implemented since mixing if-top-url and unless-* is not supported by Safari.

However, the situation tends to change with time so we should revisit it later.

Also, as a part of this task we should file a bug report to WebKit and request them unblocking this use case.