WebKit generates a scroll event whenever the scrollLeft or scrollTop properties are assigned, even if the value did not change. Firefox (and I think also IE) only fire an event if the scrollLeft/Top value actually changed, not if it is set to the previous value.
Created attachment 17197 [details] Test case
I verified on both Safari & Chrome, and the behaviour seems to be same as FF as it is printing "no scroll event". So, this issue is no more reproducible. Can any one please mark it as INVALID?
I think that the test is no longer testing what it was meant to test, because the scroll event became asynchronous. I don't know if the issue still exists.