QML properties don't hold reference of JavaScript objects

JavaScript-owned QObject are not properly reference-counted and therefore destroyed when they are only referenced by QML properties.

Text {
    property variant textHolder: null

    function createMessage()
    {
        {
            textHolder = Constructor.createObject("Hello World!");
        }
        gc();
    }
}

In this example, textHolder object is destroyed when the GC runs. If I use JavaScript global variables, everything works as expected.

Test project attached.