[shotwell] Remove "sidebar" style class from treeview

[Jens Georg <jensgeorg src gnome org>]

commit dddab55309c29604d77fa944c1188d91c74d6881
Author: Jens Georg <mail jensge org>
Date:   Sun Jun 18 21:57:07 2017 +0200

    Remove "sidebar" style class from treeview
    
    Fixes missing drop prelight
    
    https://bugzilla.gnome.org/show_bug.cgi?id=768938

 src/sidebar/Tree.vala |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
---
diff --git a/src/sidebar/Tree.vala b/src/sidebar/Tree.vala
index a3fc8bf..cfe937e 100644
--- a/src/sidebar/Tree.vala
+++ b/src/sidebar/Tree.vala
@@ -93,7 +93,6 @@ public class Sidebar.Tree : Gtk.TreeView {
     public Tree(Gtk.TargetEntry[] target_entries, Gdk.DragAction actions,
         ExternalDropHandler drop_handler) {
         set_model(store);
-        get_style_context().add_class("sidebar");
         
         Gtk.TreeViewColumn text_column = new Gtk.TreeViewColumn();
         text_column.set_expand(true);