TableView: fix the position of "filled" rows

On desktop the content cannot be scrolled when there are empty filled
rows, but on touch the content can be still flicked so the empty filled
rows must move together with the content.

Change-Id: I82e27d26a332d54c051e5d7bf9e1e0ab8e205f76
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
TextFieldStyle: more fool-proof size calculation

This ensures that such style gets a sensible default size:

    TextField {
        text: "Hello"
        style: TextFieldStyle {
            font.pixelSize: 30
            background: Rectangle { color:"lightgray" }
        }
    }

Change-Id: I370d8ad324cda09c9b085191ab452c4f8994d1d9
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>