cd: Remove unneeded code

This now works in cd proper, so it's unneeded in the function.

share/functions/cd.fish

@@ -27,12 +27,6 @@ function cd --description "Change directory"
         return $status
     end
 
-    # allow explicit "cd ." if the mount-point became stale in the meantime
-    if test "$argv" = "."
-        cd "$PWD"
-        return $status
-    end
-
     builtin cd $argv
     set -l cd_status $status