columnTranslationForOffset needs to work with column-span and with multiple column sets. Right now it only works if the column set is the first one. A column set after a span won't add in its offset like it should.
This does not block turning the new columns on.
Created attachment 229909 [details]
Since I'm so close to turning new columns on, this is covered by tests that will be enabled when the flag is flipped.
Fixed in r167677.