LibJS+LibWeb: Use new Cell::Visitor helpers to avoid manual iteration

Author: https://github.com/awesomekling
Commit: 53d0dd4a2e
Pull-request: https://github.com/SerenityOS/serenity/pull/23971
Reviewed-by: https://github.com/trflynn89

Userland/Libraries/LibWeb/HTML/MessageEvent.cpp

@@ -49,8 +49,7 @@ void MessageEvent::visit_edges(Cell::Visitor& visitor)
     Base::visit_edges(visitor);
     visitor.visit(m_data);
     visitor.visit(m_ports_array);
-    for (auto& port : m_ports)
-        visitor.visit(port);
+    visitor.visit(m_ports);
 }
 
 Variant<JS::Handle<WindowProxy>, JS::Handle<MessagePort>, Empty> MessageEvent::source() const