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/CSS/CSSAnimation.h

@@ -15,6 +15,7 @@ namespace Web::CSS {
 // https://www.w3.org/TR/css-animations-2/#cssanimation
 class CSSAnimation : public Animations::Animation {
     WEB_PLATFORM_OBJECT(CSSAnimation, Animations::Animation);
+    JS_DECLARE_ALLOCATOR(CSSAnimation);
 
 public:
     static JS::NonnullGCPtr<CSSAnimation> create(JS::Realm&);