Currently scrollbar-gutters don't rerender when scrollbar-width updates. This will fix that. Rerendering of scrollbars when scrollbar-width updates will be handled separately.
Pull request: https://github.com/WebKit/WebKit/pull/15480
Committed 265726@main (8d00d37d4960): <https://commits.webkit.org/265726@main> Reviewed commits have been landed. Closing PR #15480 and removing active labels.
<rdar://problem/111696011>