Treating non-webkit browsers differently (padding-right)

Based on https://github.com/codemirror/CodeMirror/blob/master/src/line/line_data.js#L67, I see that we only add a right-padding in webkit browsers. What was the reason for this? I’m assuming there was an inconsistency between the way WK and FF engines rendered something, at some point?

I ask because I’m working on a project where FF (v61/OSD) has rendering errors that are causing lines to collapse into one another, and it turns out that this issue is what triggers it. Perhaps FF and WK are no longer different in this way? Either way, if there’s a bug that required this at some point, would it be possible to check and see if it’s still an issue?

Could you reduce the code that triggers this issue to a minimal page?