Expand new CoreIPC serialization format to cover move of WebCoreArgumentCoders
<rdar://problem/102717379>
Pull request: https://github.com/WebKit/WebKit/pull/6860
Committed 257452@main (629347e3f7c5): <https://commits.webkit.org/257452@main> Reviewed commits have been landed. Closing PR #6860 and removing active labels.