LibWeb: Allow SVG painting to escape out of a shadow tree

The spec for the `<use>` element requires a shadow tree for the
rendered content, so we need to be able to escape shadow trees when
rendering svg content.

Userland/Libraries/LibWeb/DOM/Node.h

@@ -636,6 +636,15 @@ public:
         return nullptr;
     }
 
+    template<typename U>
+    U const* shadow_including_first_ancestor_of_type() const
+    {
+        return const_cast<Node*>(this)->template shadow_including_first_ancestor_of_type<U>();
+    }
+
+    template<typename U>
+    U* shadow_including_first_ancestor_of_type();
+
     bool is_parent_of(Node const& other) const
     {
         for (auto* child = first_child(); child; child = child->next_sibling()) {

Userland/Libraries/LibWeb/DOM/ParentNode.h

@@ -55,6 +55,16 @@ private:
 template<>
 inline bool Node::fast_is<ParentNode>() const { return is_parent_node(); }
 
+template<typename U>
+inline U* Node::shadow_including_first_ancestor_of_type()
+{
+    for (auto* ancestor = parent_or_shadow_host(); ancestor; ancestor = ancestor->parent_or_shadow_host()) {
+        if (is<U>(*ancestor))
+            return &verify_cast<U>(*ancestor);
+    }
+    return nullptr;
+}
+
 template<typename Callback>
 inline void ParentNode::for_each_child(Callback callback) const
 {

Userland/Libraries/LibWeb/Layout/SVGGeometryBox.cpp

@@ -19,7 +19,7 @@ SVGGeometryBox::SVGGeometryBox(DOM::Document& document, SVG::SVGGeometryElement&
 
 CSSPixelPoint SVGGeometryBox::viewbox_origin() const
 {
-    auto* svg_box = dom_node().first_ancestor_of_type<SVG::SVGSVGElement>();
+    auto* svg_box = dom_node().shadow_including_first_ancestor_of_type<SVG::SVGSVGElement>();
     if (!svg_box || !svg_box->view_box().has_value())
         return { 0, 0 };
     return { svg_box->view_box().value().min_x, svg_box->view_box().value().min_y };
@@ -29,7 +29,7 @@ Optional<Gfx::AffineTransform> SVGGeometryBox::layout_transform() const
 {
     auto& geometry_element = dom_node();
     auto transform = geometry_element.get_transform();
-    auto* svg_box = geometry_element.first_ancestor_of_type<SVG::SVGSVGElement>();
+    auto* svg_box = geometry_element.shadow_including_first_ancestor_of_type<SVG::SVGSVGElement>();
     double scaling = 1;
     auto origin = viewbox_origin().to_type<double>().to_type<float>();
     Gfx::FloatPoint paint_offset = {};

Userland/Libraries/LibWeb/Painting/SVGGeometryPaintable.cpp

@@ -62,7 +62,7 @@ void SVGGeometryPaintable::paint(PaintContext& context, PaintPhase phase) const
     auto offset = context.floored_device_point(svg_context.svg_element_position()).to_type<int>().to_type<float>();
     painter.translate(offset);
 
-    auto const* svg_element = geometry_element.first_ancestor_of_type<SVG::SVGSVGElement>();
+    auto const* svg_element = geometry_element.shadow_including_first_ancestor_of_type<SVG::SVGSVGElement>();
     auto maybe_view_box = svg_element->view_box();
 
     auto transform = layout_box().layout_transform();

Userland/Libraries/LibWeb/SVG/SVGGraphicsElement.cpp

@@ -97,7 +97,7 @@ Gfx::AffineTransform SVGGraphicsElement::get_transform() const
 {
     // FIXME: It would be nice to do this using the SVGContext, however, then layout/hit testing knows nothing about the transform.
     Gfx::AffineTransform transform = m_transform;
-    for (auto* svg_ancestor = first_ancestor_of_type<SVGGraphicsElement>(); svg_ancestor; svg_ancestor = svg_ancestor->first_ancestor_of_type<SVGGraphicsElement>()) {
+    for (auto* svg_ancestor = shadow_including_first_ancestor_of_type<SVGGraphicsElement>(); svg_ancestor; svg_ancestor = svg_ancestor->shadow_including_first_ancestor_of_type<SVGGraphicsElement>()) {
         transform = Gfx::AffineTransform { svg_ancestor->m_transform }.multiply(transform);
     }
     return transform;
@@ -179,7 +179,7 @@ Optional<float> SVGGraphicsElement::stroke_width() const
         // FIXME: This isn't right, but it's something.
         CSSPixels viewport_width = 0;
         CSSPixels viewport_height = 0;
-        if (auto* svg_svg_element = first_ancestor_of_type<SVGSVGElement>()) {
+        if (auto* svg_svg_element = shadow_including_first_ancestor_of_type<SVGSVGElement>()) {
             if (auto* svg_svg_layout_node = svg_svg_element->layout_node()) {
                 viewport_width = svg_svg_layout_node->computed_values().width().to_px(*svg_svg_layout_node, 0);
                 viewport_height = svg_svg_layout_node->computed_values().height().to_px(*svg_svg_layout_node, 0);