Leaflet/Leaflet — pull request #1365 by joschka (2013-02-09 18:01:25+00:00)
Title: Fix viewport offset calculation in Firefox (fixes issue #1322)

`document.body.scrollTop/Left` is always `0` in Firefox, but `document.documentElement.scrollTop/Left` can be used instead.

Probably it was only forgotten to add, because `L.DomEvent.getMousePosition` does it right already (uses both).