Bug 263955

Summary:	Twelve css WPTs are failing with async overflow scrolling enabled on macOS
Product:	WebKit	Reporter:	Abrar Rahman Protyasha <a_protyasha>
Component:	Tools / Tests	Assignee:	Nobody <webkit-unassigned>
Status:	NEW ---
Severity:	Normal	CC:	a_protyasha, webkit-bug-importer
Priority:	P2	Keywords:	InRadar
Version:	WebKit Nightly Build
Hardware:	Unspecified
OS:	Unspecified
See Also:	https://bugs.webkit.org/show_bug.cgi?id=263810

Description Abrar Rahman Protyasha 2023-10-31 01:41:12 PDT

Eight WPTs from the `css/` directory are failing in ToT with the `AsyncOverflowScrollingEnabled` web preference set to true. A couple of the failures are not concerning, but at any rate, here is a summary.

The failed tests:
imported/w3c/web-platform-tests/css/compositing/mix-blend-mode/mix-blend-mode-parent-element-overflow-scroll.html
imported/w3c/web-platform-tests/css/css-grid/grid-model/grid-container-scrollbar-vertical-lr-001.html
imported/w3c/web-platform-tests/css/css-grid/grid-model/grid-container-scrollbar-vertical-rl-001.html
imported/w3c/web-platform-tests/css/css-masking/clip/clip-rect-scroll.html
imported/w3c/web-platform-tests/css/css-overflow/overflow-auto-scrollbar-gutter-intrinsic-003.html
imported/w3c/web-platform-tests/css/css-position/position-fixed-scroll-nested-fixed.html
imported/w3c/web-platform-tests/css/css-scrollbars/textarea-scrollbar-width-none.html
imported/w3c/web-platform-tests/css/css-ui/outline-negative-offset-composited-scroll.html

Of these eight tests, `imported/w3c/web-platform-tests/css/css-overflow/overflow-auto-scrollbar-gutter-intrinsic-003.html` and `imported/w3c/web-platform-tests/css/css-scrollbars/textarea-scrollbar-width-none.html` only have a 0.01% image diff, and shouldn't really be failing.

While the other tests have regressed, they now show the same failure mode as what WebDriver produces (i.e. WKTR test results and wpt.fyi test results match).

Comment 1 Radar WebKit Bug Importer 2023-10-31 01:41:23 PDT

<rdar://problem/117728258>

Comment 2 Abrar Rahman Protyasha 2023-11-01 00:47:36 PDT

Adding four more WPTs to the list of failures:

imported/w3c/web-platform-tests/css/css-scroll-snap/snap-inline-block.html
imported/w3c/web-platform-tests/css/css-transforms/transform3d-preserve3d-001.html
imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-element.html
imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-smooth-positions.html