The nautilus_[directory,file]_is_local() methods have been confounding
the concepts of "native" and "non-remote" files, ever since the port
from gnome-vfs to GIO in 59511dfee330102ee42e09bef37cbc9cd12973c6

This conceptual mismatch is notorious in the Trash location, which is
neither native nor remote. This soon raised a bug [1], which has been
worked around by introducing a check for nautilus_file_is_in_trash().

Now, after the previous commits, the is_local() methods are no longer
employed to check that files are "non-remote". Instead, we now use
nautilus_file_is_remote(), which correctly reports that the trash is
not remote.

So, this workaround can be droped now.

[1] https://bugzilla.gnome.org/show_bug.cgi?id=546353