This is not beneficial in terms of performance, and since don't take zapped-ness into account when determining whether or not a block is empty to free it, it unintentionally causes pre-mature freeing of blocks.
This was a regression introduced in http://trac.webkit.org/changeset/121316.
Created attachment 163505 [details] Patch
Comment on attachment 163505 [details] Patch Clearing flags on attachment: 163505 Committed r128262: <http://trac.webkit.org/changeset/128262>
All reviewed patches have been landed. Closing bug.
*** Bug 95516 has been marked as a duplicate of this bug. ***