LibWeb: Allow references via xlink:href for SVG <use> elements

Author: https://github.com/MacDue
Commit: https://github.com/SerenityOS/serenity/commit/0a061a6a63
Pull-request: https://github.com/SerenityOS/serenity/pull/23736
Issue: https://github.com/SerenityOS/serenity/issues/19648
Issue: https://github.com/SerenityOS/serenity/issues/23006
Reviewed-by: https://github.com/nico

Userland/Libraries/LibWeb/SVG/SVGUseElement.cpp

@@ -58,8 +58,7 @@ void SVGUseElement::attribute_changed(FlyString const& name, Optional<String> co
         m_x = AttributeParser::parse_coordinate(value.value_or(String {}));
     } else if (name == SVG::AttributeNames::y) {
         m_y = AttributeParser::parse_coordinate(value.value_or(String {}));
-    } else if (name == SVG::AttributeNames::href) {
-        // FIXME: Support the xlink:href attribute as a fallback
+    } else if (name == SVG::AttributeNames::href || name == "xlink:href"_fly_string) {
         m_referenced_id = parse_id_from_href(value.value_or(String {}));
 
         clone_element_tree_as_our_shadow_tree(referenced_element());