LibWeb: Add calls to JS_{DECLARE,DEFINE}_ALLOCATOR()

Author: https://github.com/mattco98
Commit: 31341b280a
Pull-request: https://github.com/SerenityOS/serenity/pull/23878
Issue: https://github.com/SerenityOS/serenity/issues/23805
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibWeb/Layout/SVGMaskBox.h

@@ -14,6 +14,7 @@ namespace Web::Layout {
 
 class SVGMaskBox : public SVGGraphicsBox {
     JS_CELL(SVGMaskBox, SVGBox);
+    JS_DECLARE_ALLOCATOR(SVGMaskBox);
 
 public:
     SVGMaskBox(DOM::Document&, SVG::SVGMaskElement&, NonnullRefPtr<CSS::StyleProperties>);