It has been disabled for a while now.
<rdar://problem/115056572>
Created attachment 467566 [details] Patch
Created attachment 467567 [details] [fast-cq]Patch
Committed 267728@main (43af59838198): <https://commits.webkit.org/267728@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 467567 [details].
Hi, Was this change discussed? Frame flattening is an important feature for embedded browsers, e.g. its essential when browsing web on TV screen with remote control.