QmlDesigner: avoid setContext warning if there is already one

Change-Id: I2d23f8f18cce11bdfbdcb4a8d9d6d99fec7d20e6
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>

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

@@ -1158,7 +1158,7 @@ QObject *ObjectNodeInstance::createPrimitive(const QString &typeName, int majorN
 
     tweakObjects(object);
 
-    if (object)
+    if (object && QQmlEngine::contextForObject(object) == 0)
         QQmlEngine::setContextForObject(object, context);
 
     QQmlEngine::setObjectOwnership(object, QQmlEngine::CppOwnership);