[gnome-builder] themes: remove dead code

[Christian Hergert <chergert src gnome org>]

commit 781b2cd9097de71c68e5bcac99660cc7431b9c2f
Author: Christian Hergert <chergert redhat com>
Date:   Fri Jun 28 15:30:01 2019 -0700

    themes: remove dead code

 src/libide/themes/themes/shared/shared-treeview.css | 8 --------
 1 file changed, 8 deletions(-)
---
diff --git a/src/libide/themes/themes/shared/shared-treeview.css 
b/src/libide/themes/themes/shared/shared-treeview.css
index 884668191..9f595fb90 100644
--- a/src/libide/themes/themes/shared/shared-treeview.css
+++ b/src/libide/themes/themes/shared/shared-treeview.css
@@ -17,11 +17,3 @@ treeview.i-wanna-be-listbox:selected:backdrop {
   color: @theme_unfocused_selected_fg_color;
   background-color: @theme_unfocused_selected_bg_color;
 }
-
-ideeditorsidebar treeview.testing-tree {
-  -GtkTreeView-expander-size: 0;
-  -GtkTreeView-horizontal-separator: 0;
-  -GtkTreeView-vertical-separator: 6;
-  -gtk-icon-source: none;
-  padding-left: 6px;
-}