When the kinetic scrolling reduces it's speed, there can be multiple frames where the movement is zero pixels (followed by a 1 pixel movement later on).
This causes a "jitter" right at the end of the scroll which makes it feel less quality than other platforms. Instead, we should just clamp it as soon as we get a zero movement.
This is what I put in Gtk+ to avoid the same issue.
Created attachment 317927 [details]
Thank you Christian!
Committed r220638: <http://trac.webkit.org/changeset/220638>