https://css-tricks.com/css-scroll-snap-slide-deck/ describes a slide deck using scroll snap for the slides. In the result <https://codepen.io/5t3ph/full/yLzQeGr/652097fa9ce1150aeb5400637ab91b63>, moving between slides via the keyboard doesn't animate in Safari, but odes in Chrome and Firefox.
<rdar://problem/88574200>
Created attachment 453279 [details] Patch
https://trac.webkit.org/changeset/290548/webkit
Reverted in https://trac.webkit.org/changeset/290604/webkit
Created attachment 453402 [details] Patch
I think the tests are passing for me because the default value for ScrollAnimatorEnabled comes from the NSScrollAnimationEnabled default.
Also NSScrollAnimationEnabled is 1 when read in the web process, and 0 when read in the UI process (when there's a stale default left around)
Created attachment 453433 [details] Patch
Committed r290625 (247898@main): <https://commits.webkit.org/247898@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 453433 [details].