Folder View: only push dir contents onto history stack in list view

The check for whether we should open a dir in the file manager or push
its contents onto the history stack should have been checking for
whether the representation is list view, but this was erroneously
removed by me in d5abf12d6661f2a8f8449d9abe88468114a73dcawhen fixing
something else. Fixed now.

BUG: 471190
FIXED-IN: 6.0