[Development] QSize/Rect::grownBy/shrunkBy

[Mutz, Marc]

Hi,

I need a thumbs up or down, finally, on

   https://codereview.qt-project.org/c/qt/qtbase/+/262894 (3x +1 already)
   https://codereview.qt-project.org/c/qt/qtbase/+/266737

Thanks,
Marc