It is available from the GraphicsLayer.
Created attachment 377948 [details] patch
Created attachment 377949 [details] patch
Created attachment 377953 [details] patch
Comment on attachment 377953 [details] patch Clearing flags on attachment: 377953 Committed r249455: <https://trac.webkit.org/changeset/249455>
All reviewed patches have been landed. Closing bug.
<rdar://problem/55006081>