LibWeb/CSS: Use CSS::URL for <url> and <paint> types

Author: https://github.com/AtkinsSJ
Commit: 326933cd93
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4531

Libraries/LibWeb/SVG/SVGGraphicsElement.h

@@ -8,6 +8,7 @@
 #pragma once
 
 #include <LibGfx/PaintStyle.h>
+#include <LibWeb/CSS/URL.h>
 #include <LibWeb/DOM/Node.h>
 #include <LibWeb/SVG/AttributeParser.h>
 #include <LibWeb/SVG/SVGAnimatedTransformList.h>
@@ -91,6 +92,21 @@ protected:
         return {};
     }
 
+    template<typename T>
+    GC::Ptr<T> try_resolve_url_to(CSS::URL const& url) const
+    {
+        // FIXME: Complete and use the entire URL, not just the fragment.
+        Optional<FlyString> fragment;
+        if (auto fragment_offset = url.url().find_byte_offset('#'); fragment_offset.has_value()) {
+            fragment = MUST(url.url().substring_from_byte_offset_with_shared_superstring(fragment_offset.value() + 1));
+        }
+        if (!fragment.has_value())
+            return {};
+        if (auto node = document().get_element_by_id(*fragment); node && is<T>(*node))
+            return static_cast<T&>(*node);
+        return {};
+    }
+
 private:
     virtual bool is_svg_graphics_element() const final { return true; }
     float resolve_relative_to_viewport_size(CSS::LengthPercentage const& length_percentage) const;