Move some more "softlinked wrapper" classes across to the new CoreIPC serialization format
<rdar://problem/102772747>
Pull request: https://github.com/WebKit/WebKit/pull/6923
Committed 257254@main (7303ffa1082a): <https://commits.webkit.org/257254@main> Reviewed commits have been landed. Closing PR #6923 and removing active labels.