Revert part of 20b0cb68

That commit, which disregarded roles with empty text for the row number
calculation in Icons View, caused the problem that icons might jump
around while information was retrieved asynchronously because previously
empty roles could get a non-empty value, and the corresponding items
would need an additional row in the view.

Thanks to Hrvoje Senjan for testing this feature in master and reporting
this issue early, such that we could fix it quickly and prevent that
other users suffer from this bug!

CCBUG: 304752