Implement point-mapping changes for css 3d transforms interop.
<rdar://problem/102632597>
Pull request: https://github.com/WebKit/WebKit/pull/6772
Committed 257432@main (96c4f6e9ec7c): <https://commits.webkit.org/257432@main> Reviewed commits have been landed. Closing PR #6772 and removing active labels.