commit d85e5739ea8939415b0e8ce9a16e616ad8abf385
Author: Joel Pittet <joel@pittet.ca>
Date:   Tue Apr 16 09:58:58 2013 -0700

    remove bartik theme_hook and replace with twig file

diff --git a/core/themes/bartik/bartik.theme b/core/themes/bartik/bartik.theme
index 9a6c8a9..9cf9040 100644
--- a/core/themes/bartik/bartik.theme
+++ b/core/themes/bartik/bartik.theme
@@ -121,13 +121,6 @@ function bartik_preprocess_block(&$variables) {
 }
 
 /**
- * Implements theme_menu_tree().
- */
-function bartik_menu_tree($variables) {
-  return '<ul class="menu clearfix">' . $variables['tree'] . '</ul>';
-}
-
-/**
  * Implements theme_field__field_type().
  */
 function bartik_field__taxonomy_term_reference($variables) {
diff --git a/core/themes/bartik/templates/menu-tree.html.twig b/core/themes/bartik/templates/menu-tree.html.twig
new file mode 100644
index 0000000..0a88f42
--- /dev/null
+++ b/core/themes/bartik/templates/menu-tree.html.twig
@@ -0,0 +1,20 @@
+{#
+/**
+ * @file
+ * Bartik's theme implementation for the wrapper of a menu tree.
+ *
+ * Available variables:
+ * - tree: An HTML string containing the tree's items.
+ *
+ * Note: Each item in the menu tree can be individually themed in
+ * menu-link.html.twig.
+ *
+ * @see template_preprocess()
+ * @see template_preprocess_menu_tree()
+ *
+ * @ingroup themeable
+ */
+#}
+<ul class="menu clearfix">
+  {{ tree }}
+</ul>