Hi Team, Based on discussion with Ryosuke on Slack, it seems that the function should have "containsIncludingShadowDOM" rather than just "contain". https://github.com/WebKit/WebKit/blob/af67e80850c1e752b05548a41f4d507272c8e7bf/Source/WebCore/page/EventHandler.cpp#L431 This bug is just to fix this and have ShadowDOM coverage. Thanks!
Committed 258122@main (3499e2bc4f43): <https://commits.webkit.org/258122@main> Reviewed commits have been landed. Closing PR #7868 and removing active labels.
<rdar://problem/103544698>