QmlDesigner.model: fix majorQtQuickVersion()

This function was broken for Item.

Change-Id: I772a2fd1b63933ba1134c824eb245b78d0270d9d
Reviewed-by: Marco Bubke <marco.bubke@digia.com>

src/plugins/qmldesigner/designercore/model/modelnode.cpp

@@ -249,10 +249,12 @@ int ModelNode::majorQtQuickVersion() const
     }
 
     if (metaInfo().isValid()) {
+        if (type() == "QtQuick.QtObject")
+            return majorVersion();
         NodeMetaInfo superClass = metaInfo().directSuperClass();
 
         while (superClass.isValid()) {
-            if (superClass.typeName() == "QtQuick.Item")
+            if (superClass.typeName() == "QtQuick.QtObject")
                 return superClass.majorVersion();
             superClass = superClass.directSuperClass();
         }