LibWeb: Add const versions of SVGBox::dom_node() and friends

Author: https://github.com/AtkinsSJ
Commit: 49fe232bc7
Pull-request: https://github.com/SerenityOS/serenity/pull/12444
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibWeb/Layout/SVGPathBox.h

@@ -17,6 +17,7 @@ public:
     virtual ~SVGPathBox() override = default;
 
     SVG::SVGPathElement& dom_node() { return verify_cast<SVG::SVGPathElement>(SVGGraphicsBox::dom_node()); }
+    SVG::SVGPathElement const& dom_node() const { return verify_cast<SVG::SVGPathElement>(SVGGraphicsBox::dom_node()); }
 
     virtual void paint(PaintContext& context, PaintPhase phase) override;