We have experience a huge regression on Mac PLT after <http://trac.webkit.org/changeset/197981>: (rdar://problem/25113391). So disable the feature until the performance issue is resolved.
Created attachment 273987 [details]
Comment on attachment 273987 [details]
Clearing flags on attachment: 273987
Committed r198145: <http://trac.webkit.org/changeset/198145>
All reviewed patches have been landed. Closing bug.
The bots did not recover after this change.
Reverted r198145 for reason:
This attempt to disable the feature did not fix the PLT regression
Committed r198188: <http://trac.webkit.org/changeset/198188>