QmlDesigner: Remove old function

Change-Id: I065a6febd74e13740117e0a5223fa71648a7c430
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

share/qtcreator/qml/qmlpuppet/qml2puppet/instances/qt5previewnodeinstanceserver.cpp

@@ -96,14 +96,6 @@ void Qt5PreviewNodeInstanceServer::changeState(const ChangeStateCommand &/*comma
 
 }
 
-static void updateDirtyNodeRecursive(QQuickItem *parentItem)
-{
-    foreach (QQuickItem *childItem, parentItem->childItems())
-        updateDirtyNodeRecursive(childItem);
-
-    DesignerSupport::updateDirtyNode(parentItem);
-}
-
 QImage Qt5PreviewNodeInstanceServer::renderPreviewImage()
 {
     rootNodeInstance().updateDirtyNodeRecursive();