LibWeb: Make DOM::Event and all its subclasses GC-allocated

Author: https://github.com/awesomekling
Commit: 7c3db526b0
Pull-request: https://github.com/SerenityOS/serenity/pull/14816
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibWeb/HTML/MessagePort.cpp

@@ -80,7 +80,7 @@ void MessagePort::post_message(JS::Value message)
         MessageEventInit event_init {};
         event_init.data = message;
         event_init.origin = "<origin>";
-        strong_port->dispatch_event(MessageEvent::create(HTML::EventNames::message, event_init));
+        strong_port->dispatch_event(*MessageEvent::create(verify_cast<Bindings::WindowObject>(strong_port->wrapper()->global_object()), HTML::EventNames::message, event_init));
     }));
 }