URL default ports

[daxpedda]

Fabruic shouldn't support any default ports, even for https and the like. This is currently limited through the URL parser.

See servo/rust-url#706.

[daxpedda]

Fixed by servo/rust-url#707.

[daxpedda]

My PR was declined by the Url team, it seems it might not be in scope, for now. As we don't plan to write our own URL-parsing crate, I will close this, we can re-open if Url changes their mind.