Regression: Object.keys() exposes hidden methods

The following snippet exposes the intentionally hidden methods deleteLater and destroyed (though typeof === "undefined" for them) starting with Qt 5.2:

import QtQuick 2.0
QtObject {
    id: myObj
    Component.onCompleted: console.log(Object.keys(myObj))
}

Prior to Qt 5.2 this produced:
[objectName,onObjectNameChanged,objectNameChanged]

Now it produces:
[objectName,destroyed,destroyed,objectNameChanged,deleteLater,_q_reregisterTimers]