[gnome-robots] Do not use global variable in methods

[Andrey Kutejko <akutejko src gnome org>]

commit 43e2151bda71b29ef6849377ddf6036dc8f72ab3
Author: Andrey Kutejko <andy128k gmail com>
Date:   Sun Sep 27 17:00:40 2020 +0200

    Do not use global variable in methods

 src/themes.vala | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/themes.vala b/src/themes.vala
index be452ce..07ce5d4 100644
--- a/src/themes.vala
+++ b/src/themes.vala
@@ -121,7 +121,7 @@ public class Themes : Gtk.ListStore {
             return iter;
         }
 
-        if (themes.get_iter_first (out iter)) {
+        if (get_iter_first (out iter)) {
             return iter;
         } else {
             throw new FileError.NOENT ("No theme was found.");
@@ -133,7 +133,7 @@ public class Themes : Gtk.ListStore {
 
         string theme_name;
         string theme_path;
-        themes.get_values (iter, out theme_name, out theme_path);
+        get_values (iter, out theme_name, out theme_path);
 
         return new Theme.from_file (theme_path, theme_name);
     }