[abp2blocklist] Improve $genericblock support using unless-top-url

[mjethani]

Background

In #4329 we added limited support for $genericblock using the unless-domain property. Apple has added a ​new property in Safari 11 called unless-top-url, which takes a URL pattern instead of just a domain name. Now we can whitelist specific URL patterns instead of whitelisting the entire domain. Since Safari ignores any properties it does not recognize, we can start using this property in our content blocker rules right away.

What to change

Instead of unless-domain, use unless-top-url to implement $genericblock. Add any URL pattern to the list, even if it doesn't contain the hostname.

Continue to use unless-domain to support older versions of Safari based on a configuration flag.

[sebastian]

For reference, this change would unsupport $genericblock on Safari <=10, again. But FWIW, I think this is fine, if we can get more accurrate behavior on newer Safari versions, and possibly also simplify the code, with this change.

Also note that we could potentially make $document whitelisting more accurately as well using if-top-url, as they are supposed to be recursive.

[sebastian]

abp2blocklist has been ​moved from the Platform module to Adblock Plus for iOS/macOS.