Do not force focus for non-focused windows.

If a QQuickWindow comes to screen but is not the focus window,
such as if it is a child window of another window, it should
not have focus by default.

Change-Id: If9015bbc179bb101178b3bc8de176a1c71c46023
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Andy Nichols <andy.nichols@digia.com>