Allow whitelisting of second-level domains

[tung]

99.9% of the time, when you want to allow JavaScript on www.example.com, you also want to allow it for example.com, cdn.example.com, blog.example.com, etc. the so-called second-level domains.

SomeScript should either do this by default, or provide it as an option. NoScript allows this as an option.

[tung]

nsIEffectiveTLDService allows me to get those second-level domains through its getBaseDomainFromHost function. That makes it easy to whitelist on and check against a list of second-level domains.

The hard part is blocking. I can listen on nsIWebProgress with a nsIWebProgressListener, but how would I actually allow/block JavaScript requests?