If you right-click on an element in the Elements tab of the Web Inspector, there is an option to "Reveal in Layers Tab" even if the Layers Tab has not been enabled via the experimental settings. It seems like it should probably be hidden until the Layers Tab is no longer considered experimental.
Created attachment 365352 [details] Patch
Comment on attachment 365352 [details] Patch Do have tests for this type of thing?
Comment on attachment 365352 [details] Patch r=me
Comment on attachment 365352 [details] Patch Clearing flags on attachment: 365352 Committed r243224: <https://trac.webkit.org/changeset/243224>
All reviewed patches have been landed. Closing bug.
<rdar://problem/49073152>