See the patch. (Yes, name's the same as in bug 194943)
Created attachment 380340 [details]
Comment on attachment 380340 [details]
View in context: https://bugs.webkit.org/attachment.cgi?id=380340&action=review
> + deltaX *= (double) Scrollbar::pixelsPerLineStep() / m_distance;
I know this is na existing issue, but please use C++ style cast.
Created attachment 380416 [details]
Comment on attachment 380416 [details]
Clearing flags on attachment: 380416
Committed r250820: <https://trac.webkit.org/changeset/250820>
All reviewed patches have been landed. Closing bug.