LibWeb/DOM: Visit the animation of Document's pending animations

Author: https://github.com/LucasChollet
Commit: https://github.com/LadybirdBrowser/ladybird/commit/589538ec8f7
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3064
Reviewed-by: https://github.com/trflynn89 ✅

Libraries/LibWeb/DOM/Document.cpp

@@ -525,6 +525,7 @@ void Document::visit_edges(Cell::Visitor& visitor)
 
     for (auto& event : m_pending_animation_event_queue) {
         visitor.visit(event.event);
+        visitor.visit(event.animation);
         visitor.visit(event.target);
     }