Drop IPC::Encoder::buffer() / bufferSize(), in favor of span().
Pull request: https://github.com/WebKit/WebKit/pull/28967
Committed 279231@main (def81c6ee83a): <https://commits.webkit.org/279231@main> Reviewed commits have been landed. Closing PR #28967 and removing active labels.
<rdar://problem/128635035>