bug#42406: Mouse-wheel scrolling can be flickering

[martin rudalics]

>> Does the line number displayed in the mode line update correctly when
>> you do that and scroll the window?
>
> Yes, as before. Should there be a problem now?

Not necessarily.  If you don't see any problems there, the calls in
window_scroll_pixel_based could be possibly removed since that case
should be covered elsewhere.

martin