A set of settings to control accelerated compositing has long been replaced with triggers returned by ChromeClient, but haven't been fully removed. They are only set by the Qt port but not read anywhere.
Created attachment 207329 [details] Patch
Comment on attachment 207329 [details] Patch Clearing flags on attachment: 207329 Committed r153055: <http://trac.webkit.org/changeset/153055>
All reviewed patches have been landed. Closing bug.