scripting: get CreateUnoDialog() work again

Trivial reproducer:

Dim Dlg As Object
DialogLibraries.LoadLibrary("Standard")
Dlg = CreateUnoDialog(DialogLibraries.Standard.Dialog1)
Dlg.Execute()
Dlg.dispose()

Regression from 6c61b20a.

Change-Id: Ia62778c6d94f54e6097a307701e5c81be847665d
Reviewed-on: https://gerrit.libreoffice.org/4023Reviewed-by: Miklos Vajna <vmiklos@suse.cz>
Tested-by: Miklos Vajna <vmiklos@suse.cz>

scripting/source/dlgprov/dlgprov.cxx

@@ -149,9 +149,10 @@ static OUString aResourceResolverPropName("ResourceResolver");
         // Set resource property
         if( xStringResourceManager.is() )
         {
+            Reference< beans::XPropertySet > xDlgPSet( xDialogModel, UNO_QUERY );
             Any aStringResourceManagerAny;
             aStringResourceManagerAny <<= xStringResourceManager;
-            xDialogModel->setPropertyValue( aResourceResolverPropName, aStringResourceManagerAny );
+            xDlgPSet->setPropertyValue( aResourceResolverPropName, aStringResourceManagerAny );
         }
 
         return xDialogModel;