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/CanvasBox.h

@@ -13,6 +13,7 @@ namespace Web::Layout {
 
 class CanvasBox final : public ReplacedBox {
     JS_CELL(CanvasBox, ReplacedBox);
+    JS_DECLARE_ALLOCATOR(CanvasBox);
 
 public:
     CanvasBox(DOM::Document&, HTML::HTMLCanvasElement&, NonnullRefPtr<CSS::StyleProperties>);