Which is why I mentioned both Chrome and Firefox, as while both implement some non-standard features, those tend to differ, so the intersection of their feature

Which is why I mentioned both Chrome and Firefox, as while both implement some non-standard features, those tend to differ, so the intersection of their feature sets is pretty much the standard itself. I was actually referring to "your extensions following the standard", but since you can't exactly test against the standard directly, I used testing against both browsers as a good approximation.