Port ControlPart related controls to the new IPC serialization format
<rdar://problem/115781032>
Pull request: https://github.com/WebKit/WebKit/pull/17972
Committed 270445@main (a7330e04e710): <https://commits.webkit.org/270445@main> Reviewed commits have been landed. Closing PR #17972 and removing active labels.
Seems to have caused a +0.58 MB binary size increase (rdar://118179198).
Re-opened since this is blocked by bug 264536
Pull request: https://github.com/WebKit/WebKit/pull/23741
(In reply to Gavin from comment #6) > Pull request: https://github.com/WebKit/WebKit/pull/23741 I have a PR here that requires very little refactoring: https://github.com/WebKit/WebKit/pull/23713