Computing offsetX/Y is non-trivial, and the values are meaningless for simulated clicks anyway.
Created attachment 225448 [details]
Comment on attachment 225448 [details]
View in context: https://bugs.webkit.org/attachment.cgi?id=225448&action=review
> + There's no need to compute the exact target-relative coordinates for
> + simulated mouse events, e.g those fired by HTMLElement.click().
r=me with the condition that this matches at least Firefox.
Committed r164871: <http://trac.webkit.org/changeset/164871>