Bug 275739 – REGRESSION (276531@main): Content flash when expanding image viewer on eBay page

• Status: RESOLVED
• Resolution: FIXED
• Component: Animations

[Antoine Quint]

With a recent STP, such as STP 196, load an eBay listing, such as https://www.ebay.com/itm/355596559276, and click the button the button to expand the image gallery (the double arrow next to the main listing image). Now exit the image viewer, and enter it again. You'll notice this second time, and all the times following that, a flash of the image viewer before it fades in. This does not happen on system Safari on macOS 14.5, or Chrome or Firefox. This has regressed with 276531@main.

[Antoine Quint]

rdar://128178476

[Antoine Quint]

Pull request: https://github.com/WebKit/WebKit/pull/30047

[Antoine Quint]

Created attachment 471830 [details]
Testcase

It took a while but I worked out a reduction. The issue is that if an element has an animation within a container with `display: none`, touching the style on that container will resume the animation on the child, even though `display: none` is still in play.

[Antoine Quint]

Created attachment 471831 [details]
Testcase

[Antoine Quint]

Submitted web-platform-tests pull request: https://github.com/web-platform-tests/wpt/pull/47084

[EWS]

Committed 280876@main (d08faf9fab62): <https://commits.webkit.org/280876@main>

Reviewed commits have been landed. Closing PR #30047 and removing active labels.