"ItemBuffer" in the item name helps to clarify that this item is about changing (or swapping) between display list item buffers, rather than image buffers.
Created attachment 414510 [details] Patch
Committed r270006: <https://trac.webkit.org/changeset/270006> All reviewed patches have been landed. Closing bug and clearing flags on attachment 414510 [details].
<rdar://problem/71567220>