Bug 760020 – Remove leftover support for single-file skins.

Bugzilla/User/Setting/Skin.pm

@@ -30,12 +30,8 @@ sub legal_values {
 
     foreach my $direntry (glob(catdir($dirbase, '*'))) {
         if (-d $direntry) {
-            # Stylesheet set
             next if basename($direntry) =~ /^cvs$/i;
-            push(@legal_values, basename($direntry));
-        }
-        elsif ($direntry =~ /\.css$/) {
-            # Single-file stylesheet
+            # Stylesheet set found
             push(@legal_values, basename($direntry));
         }
     }