Implement Element::set_url_attribute

[dlrobertson]

Element::set_url_attribute the counterpart to Element::get_url_attribute is not implemented yet. Once implemented the macro make_url_setter should use the new method instead of Element::set_string_attribute.

Related to: #22563 (comment) and #22454

[shanavas786]

@highfive assign me

[highfive]

Hey @shanavas786! Thanks for your interest in working on this issue. It's now assigned to you!

[nox]

https://html.spec.whatwg.org/#reflecting-content-attributes-in-idl-attributes

If a reflecting IDL attribute is a USVString attribute whose content attribute is defined to contain a URL, then on getting, if the content attribute is absent, the IDL attribute must return the empty string. Otherwise, the IDL attribute must parse the value of the content attribute relative to the element's node document and if that is successful, return the resulting URL string. If parsing fails, then the value of the content attribute must be returned instead, converted to a USVString. On setting, the content attribute must be set to the specified new value.

I don't see why we should have a make_url_setter, given the setter is specified to have no URL-specific behaviour.

[dlrobertson]

@nox good catch

The make_url_setter is needed because the given structure has a USVString element and the setter is DOMString, so we need USVString -> DOMString, but I guess we don't necessarily need Element::set_url_attribute. We could just keep the USVString -> DOMString evaluation in the macro make_url_setter.

CC @ferjm