The Window attached property exposes all kinds of window attributes,
but not the window itself. Being able to access the window is often
useful for various purposes. For example, in QML TestCase, to be able
to access the window of the TestCase so that one can call various
slots such as requestActivate().
Change-Id: Id03c9f277bb17810b41a60957011ccf07399e149
Reviewed-by: Mitch Curtis <mitch.curtis@theqtcompany.com>
04d4dca69d