Behavior does not work properly with font.pointSize

import QtQuick 2.0

Item {
    id: main
    height: 640; width: 360

    Text {
        id: label
        text: "hello world"
        font.pointSize: 25

        Behavior on font.pointSize { NumberAnimation { duration: 2000 } }
    }

    states: [
        State {
            name: "1"
            PropertyChanges { target: label; font.pointSize: 80; font.bold: true } // Comment font.bold out
        }
    ]

    MouseArea {
        anchors.fill: parent
        onClicked: {
            if (main.state == "")
                main.state = "1"
            else
                main.state = ""
        }
    }
}