[gtk+/composite-templates] cssvalue: Don't crash when printing NULL strings

[Juan Pablo Ugarte <jpu src gnome org>]

commit 015440deabc70fc62a493769986d001d9dcd78f2
Author: Benjamin Otte <otte redhat com>
Date:   Thu Sep 27 16:23:53 2012 +0200

    cssvalue: Don't crash when printing NULL strings
    
    A NULL string should be printed as "none".

 gtk/gtkcssstringvalue.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkcssstringvalue.c b/gtk/gtkcssstringvalue.c
index 9edda64..02405f4 100644
--- a/gtk/gtkcssstringvalue.c
+++ b/gtk/gtkcssstringvalue.c
@@ -65,6 +65,12 @@ gtk_css_value_string_print (const GtkCssValue *value,
   char *string = value->string;
   gsize len;
 
+  if (string == NULL)
+    {
+      g_string_append (str, "none");
+      return;
+    }
+
   g_string_append_c (str, '"');
 
   do {