This patch updates our ArgumentCodersCocoa logic to properly handle NSAttributedString. This new implementation now matches the behavior of the Foundation framework. This also allows us to unskip two tests on Big Sur (and earlier) that would fail during decoding.
<rdar://problem/100640104>
Pull request: https://github.com/WebKit/WebKit/pull/4884
Committed 255076@main (171714d05e19): <https://commits.webkit.org/255076@main> Reviewed commits have been landed. Closing PR #4884 and removing active labels.