the warning dialog's "trust this domain" toggle saves the whole
hostname, so this code needs to use the whole hostname
otherwise trusting a `www.example.com` will never work, because we'd
be checking `example.com` against it, and fail
while I was there, I also made the `trustedLinkUrlPatterns` correctly
match sub-domains: previously, trusting `ple.com` would trust
`example.com`