ScrollingTree should have the final say on where layers go

[Simon Fraser (smfr)]

ScrollingTree should have the final say on where layers go

[Simon Fraser (smfr)]

Created attachment 364107 [details]
Patch

[Simon Fraser (smfr)]

Created attachment 364110 [details]
Patch

[EWS Watchlist]

Comment on attachment 364110 [details]
Patch

Attachment 364110 [details] did not pass mac-wk2-ews (mac-wk2):
Output: https://webkit-queues.webkit.org/results/11441789

New failing tests:
accessibility/mac/selection-notification-focus-change.html

[EWS Watchlist]

Created attachment 364145 [details]
Archive of layout-test-results from ews107 for mac-highsierra-wk2

The attached test failures were seen while running run-webkit-tests on the mac-wk2-ews.
Bot: ews107  Port: mac-highsierra-wk2  Platform: Mac OS X 10.13.6

[Simon Fraser (smfr)]

Created attachment 364182 [details]
Patch

[Simon Fraser (smfr)]

https://trac.webkit.org/changeset/242687/webkit

[Radar WebKit Bug Importer]

<rdar://problem/48751114>

[Truitt Savell]

The changes in https://trac.webkit.org/changeset/242687/webkit

appears to have broken compositing/ios/overflow-scroll-update-overlap.html on iOS. It also looks like it is slowing down EWS

History:
https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=compositing%2Fios%2Foverflow-scroll-update-overlap.html

Image Diff:
https://build.webkit.org/results/Apple%20iOS%2012%20Simulator%20Release%20WK2%20(Tests)/r242700%20(3064)/compositing/ios/overflow-scroll-update-overlap-diffs.html

[Ryan Haddad]

(In reply to Truitt Savell from comment #8)
> The changes in https://trac.webkit.org/changeset/242687/webkit
> 
> appears to have broken compositing/ios/overflow-scroll-update-overlap.html
> on iOS. It also looks like it is slowing down EWS
Should we go ahead and roll this out?

[Simon Fraser (smfr)]

(In reply to Ryan Haddad from comment #9)
> (In reply to Truitt Savell from comment #8)
> > The changes in https://trac.webkit.org/changeset/242687/webkit
> > 
> > appears to have broken compositing/ios/overflow-scroll-update-overlap.html
> > on iOS. It also looks like it is slowing down EWS
> Should we go ahead and roll this out?

No, I'll look at this now.

[Simon Fraser (smfr)]

I filed bug 195584 to fix that, and marked the test as failing in r242758.

[Simon Fraser (smfr)]

*** Bug 194996 has been marked as a duplicate of this bug. ***