In deprecated chr_name call, I've changed the code so it projects to the...

In deprecated chr_name call, I've changed the code so it projects to the toplevel, not to the chromosome.  All species used to have chromosomes, so this always worked - the meaning of this call is now the same as it was, with the addded bonus that it works for species without chromosomes

modules/Bio/EnsEMBL/Gene.pm

@@ -742,15 +742,7 @@ sub chr_name {
     return $gene_slice->seq_region_name();
   }
 
-  my $sa = $self->slice->adaptor();
-  throw( "need db connection for chr_name call" ) unless $sa;
-
-  my $ca = $sa->db()->get_CoordSystemAdaptor();
-  my $coord_system = $ca->fetch_by_name( "chromosome" );
-  if( ! $coord_system ) {
-    throw( "Chromosome coordinate system not available" );
-  }
-  my $coords = $self->project( $coord_system );
+  my $coords = $self->project( "toplevel" );
 
   if( @$coords ) {
     return $coords->[0]->[2]->seq_region_name();