Specify default values for optional parameters of type 'unsigned long' and let the bindings generator use WTF::Optional<> for the parameters that do not have such default value.
Created attachment 277411 [details] Patch
Comment on attachment 277411 [details] Patch Clearing flags on attachment: 277411 Committed r200110: <http://trac.webkit.org/changeset/200110>
All reviewed patches have been landed. Closing bug.
Interestingly, this was a confirmed 1.5% PLT progression on iOS.
Which change do you think was responsible?