After 262176@main we create a new ScrollbarsController on every call to LocalFrameView::didAddScrollbar()
<rdar://problem/109909019>
Pull request: https://github.com/WebKit/WebKit/pull/14408
Committed 264690@main (003e0fd9799f): <https://commits.webkit.org/264690@main> Reviewed commits have been landed. Closing PR #14408 and removing active labels.