Convert ContentSecurityPolicyResponseHeaders to the new IPC serialization format.
Pull request: https://github.com/WebKit/WebKit/pull/20184
Committed 270417@main (0b83b4f40567): <https://commits.webkit.org/270417@main> Reviewed commits have been landed. Closing PR #20184 and removing active labels.
<rdar://problem/118148625>