While Origin is defined in the HTML spec - this leaves us with quite an
awkward relationship as the URL spec makes use of AO's from what is
defined in the HTML spec.
To simplify this factoring, relocate Origin into LibURL.
I saw a suspicious null dereference in
check_if_access_between_two_browsing_contexts_should_be_reported(),
but I have no idea how to reproduce it.
Still, it seems harmless to paper over it with a FIXME debug log.
After removing an iframe from the DOM, its contentWindow will be
detached from its browsing context, per spec.
Because the contentWindow is still accessible, we cannot assume that
Window objects always have an associated browsing context.
This needs to be fixed in the spec, but let's add a sensible null check
in the meantime.
These are from the HTML spec and therefore belong in the HTML/ directory
in LibWeb. Bindings/ has become a bit of a dumping ground, so this is a
first step towards cleaning that up.
