LibWeb: Add fast_is<T> optimization for more paintables

We were doing a lot of dynamic_cast with these types, so let's avoid it.

Author: awesomekling

Libraries/LibWeb/Painting/Paintable.h

@@ -118,10 +118,13 @@ class WEB_API Paintable
     bool fast_is() const = delete;
 
     [[nodiscard]] virtual bool is_navigable_container_viewport_paintable() const { return false; }
+    [[nodiscard]] virtual bool is_viewport_paintable() const { return false; }
     [[nodiscard]] virtual bool is_paintable_box() const { return false; }
     [[nodiscard]] virtual bool is_paintable_with_lines() const { return false; }
     [[nodiscard]] virtual bool is_svg_paintable() const { return false; }
     [[nodiscard]] virtual bool is_svg_svg_paintable() const { return false; }
+    [[nodiscard]] virtual bool is_svg_path_paintable() const { return false; }
+    [[nodiscard]] virtual bool is_svg_graphics_paintable() const { return false; }
     [[nodiscard]] virtual bool is_text_paintable() const { return false; }
 
     DOM::Document const& document() const;

Libraries/LibWeb/Painting/SVGGraphicsPaintable.h

@@ -71,6 +71,12 @@ class SVGGraphicsPaintable : public SVGPaintable
     SVGGraphicsPaintable(Layout::SVGGraphicsBox const&);
 
     ComputedTransforms m_computed_transforms;
+
+private:
+    virtual bool is_svg_graphics_paintable() const final { return true; }
 };
 
+template<>
+inline bool Paintable::fast_is<SVGGraphicsPaintable>() const { return is_svg_graphics_paintable(); }
+
 }

Libraries/LibWeb/Painting/SVGPathPaintable.h

@@ -37,6 +37,12 @@ class WEB_API SVGPathPaintable final : public SVGGraphicsPaintable {
     SVGPathPaintable(Layout::SVGGraphicsBox const&);
 
     Optional<Gfx::Path> m_computed_path = {};
+
+private:
+    virtual bool is_svg_path_paintable() const final { return true; }
 };
 
+template<>
+inline bool Paintable::fast_is<SVGPathPaintable>() const { return is_svg_path_paintable(); }
+
 }

Libraries/LibWeb/Painting/ViewportPaintable.h

@@ -45,6 +45,8 @@ class WEB_API ViewportPaintable final : public PaintableWithLines {
     ReadonlySpan<GC::Ref<PaintableBox>> paintable_boxes_with_auto_content_visibility() const { return m_paintable_boxes_with_auto_content_visibility; }
 
 private:
+    virtual bool is_viewport_paintable() const override { return true; }
+
     void build_stacking_context_tree();
 
     explicit ViewportPaintable(Layout::Viewport const&);
@@ -57,4 +59,7 @@ class WEB_API ViewportPaintable final : public PaintableWithLines {
     Vector<GC::Ref<PaintableBox>> m_paintable_boxes_with_auto_content_visibility;
 };
 
+template<>
+inline bool Paintable::fast_is<ViewportPaintable>() const { return is_viewport_paintable(); }
+
 }