We need to add a define to allow clients to adopt the delegate changes from 275950@main.
<rdar://problem/124459704>
Pull request: https://github.com/WebKit/WebKit/pull/25779
Committed 275983@main (a9eb13f5a7a4): <https://commits.webkit.org/275983@main> Reviewed commits have been landed. Closing PR #25779 and removing active labels.