Code review comment for lp://qastaging/~dandrader/unity8/availableDesktopArea

I'm wondering why we still need those restrictions in Stage.qml at all, like the minimumY for WindowStateSaver, or the boundsItem on the MoveResizeArea. I would think now that miral knows the limits the qml code should not need to care about this any more at all? Perhaps miral is not quite there yet, I'm not sure. If we still need to provide those informations to the qml code, wouldn't it make sense to at least drop root.leftMargin etc and use the availableDesktopArea item instead now?