Remove limit on "max-width" for file names in drag shadow

The general file list sets "max-width: 0" in the file names, which
causes the file names in the drag shadow to have no width for their
content and thus to overlap with the file size.

As that limit is needed for proper layout in the general file list it is
removed only for file names in drag shadows.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>