303958 2025-12-10 17:09:57 -0800 Layout milestone notifications should be dispatched asynchronously 2025-12-18 19:28:50 -0800 1 1 1 Unclassified WebKit WebKit Misc. WebKit Nightly Build Unspecified Unspecified REOPENED InRadar P2 Normal --- 304460 1 jlee53 jlee53 webkit-bug-importer oldest_to_newest 2164971 0 jlee53 2025-12-10 17:09:57 -0800 Javascript execution should not happen during in the process of updating the layout. When a layout milestone notification fires, the layout may not be completed but client callbacks to layout milestone notifications can trigger Javascript execution. This results in javascript execution failing (and consequently crashing) to run in the middle of the layout process because it is correctly not permitted to do so. We delay firing layout milestone notifications by dispatching them asychronously in order to prevent this. 2164972 1 jlee53 2025-12-10 17:10:24 -0800 <rdar://problem/153254633> 2164973 2 jlee53 2025-12-10 17:11:50 -0800 Pull request: https://github.com/WebKit/WebKit/pull/55213 2166350 3 jlee53 2025-12-16 13:46:31 -0800 Pull request: https://github.com/WebKit/WebKit/pull/55502 2166497 4 ews-feeder 2025-12-16 19:58:34 -0800 Committed 304572@main (bf24e9a12c17): <https://commits.webkit.org/304572@main> Reviewed commits have been landed. Closing PR #55213 and removing active labels. 2167156 5 cdumez 2025-12-18 19:28:49 -0800 Reopened Bugzilla. 304572@main caused a 17% PLT regression, tracking revert in https://bugs.webkit.org/show_bug.cgi?id=304460.