overscroll-behavior-x and overscroll-behavior-y are supported, but not overscroll-behavior-block and overscroll-behavior-inline.
Created attachment 453001 [details] Patch
Committed r290422 (247730@main): <https://commits.webkit.org/247730@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 453001 [details].
<rdar://problem/89410660>