WIP: Prevent storing IRI::None in a FilterValueList
Previously an (invalid) css property like: filter: url(#foo) none
would parse an IRI::None into the FilterValueList. Later, when checking that the filter list is valid, this would cause an unreachable!
panic.
This removes the usage of IRI for this case and stores the Fragment directly in the FilterValue::URL
instead, preventing this panic.
This fixes the panic described in #621 (closed), but not the refactor.
Edited by John Ledbetter