[gtk+] style context: Avoid a compiler warning

[Matthias Clasen <matthiasc src gnome org>]

commit d930ea7c1fc6aa29ee242ef0aaedbad911bed4e1
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Oct 3 22:40:27 2015 -0400

    style context: Avoid a compiler warning

 gtk/gtkstylecontext.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkstylecontext.c b/gtk/gtkstylecontext.c
index a91db3a..0217d55 100644
--- a/gtk/gtkstylecontext.c
+++ b/gtk/gtkstylecontext.c
@@ -1354,7 +1354,7 @@ gtk_style_context_list_classes (GtkStyleContext *context)
 
   classes = gtk_css_node_list_classes (context->priv->cssnode, &n_classes);
   for (i = n_classes; i > 0; i--)
-    classes_list = g_list_prepend (classes_list, g_quark_to_string (classes[i - 1]));
+    classes_list = g_list_prepend (classes_list, (gchar *)g_quark_to_string (classes[i - 1]));
 
   return classes_list;
 }