[gtk+/gtk-3-22] cssprovider: Only free bytes when they exist

[Benjamin Otte <otte src gnome org>]

commit 63f534f4b38f1752c216ee04a16741a8b325658c
Author: Benjamin Otte <otte redhat com>
Date:   Mon Feb 5 18:58:54 2018 +0100

    cssprovider: Only free bytes when they exist

 gtk/gtkcssprovider.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkcssprovider.c b/gtk/gtkcssprovider.c
index aedbf1f..880d1ad 100644
--- a/gtk/gtkcssprovider.c
+++ b/gtk/gtkcssprovider.c
@@ -1792,7 +1792,8 @@ gtk_css_provider_load_internal (GtkCssProvider *css_provider,
         gtk_css_provider_postprocess (css_provider);
     }
 
-  g_bytes_unref (free_bytes);
+  if (free_bytes)
+    g_bytes_unref (free_bytes);
 
   if (error)
     {