Sub-task of bug 240223 ; small SharedBuffer can directly be copied instead of wrapping a SharedMemory. This change will contains a segment of the original fix in bug 240223.
<rdar://problem/93881913>
Pull request: https://github.com/WebKit/WebKit/pull/1146
Committed r295337 (251356@main): <https://commits.webkit.org/251356@main> Reviewed commits have been landed. Closing PR #1146 and removing active labels.