Also remove FilterReference and replace it with Ref<Filter> and move the superclass coders to WebCoreArgumentCoders.
<rdar://problem/103960558>
Pull request: https://github.com/WebKit/WebKit/pull/8314
Committed 259862@main (c4f56fe6d1f9): <https://commits.webkit.org/259862@main> Reviewed commits have been landed. Closing PR #8314 and removing active labels.