`gesture*` events (and resulting wheel events) originating from an embedded iframe have incorrect coordinates. Notably, these coordinates do not account for the transformation between the iframe's coordinate space and the parent document's coordinate space. This is because we do not pass gesture events to subframe event handlers. Let's fix that.
rdar://105243167
Pull request: https://github.com/WebKit/WebKit/pull/21913
Committed 272176@main (c8a66bff2703): <https://commits.webkit.org/272176@main> Reviewed commits have been landed. Closing PR #21913 and removing active labels.