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/SVG/SVGDecodedImageData.h

@@ -52,6 +52,7 @@ private:
 
 class SVGDecodedImageData::SVGPageClient final : public PageClient {
     JS_CELL(SVGDecodedImageData::SVGPageClient, PageClient);
+    JS_DECLARE_ALLOCATOR(SVGDecodedImageData::SVGPageClient);
 
 public:
     static JS::NonnullGCPtr<SVGPageClient> create(JS::VM& vm, Page& page)