QmlDesigner: Don't copy/remove data property when copying all

'data' property contains node's children, so it should be ignored
during the 'copy all properties' operation.

Change-Id: Ib056409c9ad0a42ebc40f751173b7a3455d912c6
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>

src/plugins/qmldesigner/components/materialbrowser/materialbrowsermodel.cpp

@@ -403,6 +403,7 @@ void MaterialBrowserModel::copyMaterialProperties(int idx, const QString &sectio
         }
     }
     validProps.remove("objectName");
+    validProps.remove("data");
 
     if (m_allPropsCopied || dynamicPropsCopied || m_propertyGroupsObj.empty()) {
         copiedProps = validProps.values();