scope handling fix (wip)

Author: rbri

src/main/java/org/htmlunit/javascript/host/worker/DedicatedWorkerGlobalScope.java

@@ -297,7 +297,7 @@ void executeEvent(final Context cx, final MessageEvent event) {
             final Object[] args = {event};
             for (final Scriptable scriptable : handlers) {
                 if (scriptable instanceof Function handlerFunction) {
-                    handlerFunction.call(cx, this, this, args);
+                    handlerFunction.call(cx, ScriptableObject.getTopLevelScope(event), this, args);
                 }
             }
         }