Return up-to-date values when script asks for metrics (for example through getBoundingClientRect).
Pull request: https://github.com/WebKit/WebKit/pull/16311
<rdar://problem/113621956>
Committed 267449@main (62ac47b3f307): <https://commits.webkit.org/267449@main> Reviewed commits have been landed. Closing PR #16311 and removing active labels.