Bug 212983

Summary:	REGRESSION (r261841): Scrolling on Spotify page gets reset to the top
Product:	WebKit	Reporter:	Simon Fraser (smfr) <simon.fraser>
Component:	Layout and Rendering	Assignee:	Nobody <webkit-unassigned>
Status:	RESOLVED FIXED
Severity:	Normal	CC:	bfulgham, obrufau, simon.fraser, zalan
Priority:	P1	Keywords:	InRadar
Version:	Safari Technology Preview
Hardware:	Unspecified
OS:	Unspecified
See Also:	https://bugs.webkit.org/show_bug.cgi?id=209461

Description Simon Fraser (smfr) 2020-06-09 12:34:46 PDT

Load https://open.spotify.com/artist/6vWDO969PvNqNYHIOW5v0m and scroll down. Note that when new content gets added to the bottom, the scroll position is reset to the top.

What's happening is that the <div> with overflow:scroll is getting resized to some large, non-scrollable size for a while, triggering a reset of the scroll position via RenderBlock::endAndCommitUpdateScrollInfoAfterLayoutTransaction()/updateScrollInfoAfterLayout().

This doesn't happen prior to r261841. The page does hit the new code.

Comment 1 Simon Fraser (smfr) 2020-06-09 12:35:11 PDT

<rdar://problem/64142477>

Comment 2 Simon Fraser (smfr) 2020-06-09 16:15:51 PDT

Resolved by rollout: https://trac.webkit.org/changeset/262809/webkit