Don't do anything if the target object is already set

Task-Number: BAUHAUS-666
Reviewed-by: kkoehne

src/plugins/qmldesigner/designercore/instances/qmlpropertychangesnodeinstance.cpp

@@ -89,6 +89,9 @@ QObject *QmlPropertyChangesObject::targetObject() const
 
 void QmlPropertyChangesObject::setTargetObject(QObject *object)
 {
+    if (m_targetObject.data() == object)
+        return;
+
     QMutableListIterator<QDeclarativeAction> actionIterator(m_qmlActionList);
     while (actionIterator.hasNext()) {
          QDeclarativeAction &qmlAction = actionIterator.next();