[gtk+/gtk-2-24] Themes with specified gap images but no actual file crash.

[Matthias Clasen <matthiasc src gnome org>]

commit c988a258cc73d225ccd98a478da99963ec604cfa
Author: Jehan <jehan girinstud io>
Date:   Mon Nov 18 00:55:54 2013 +1300

    Themes with specified gap images but no actual file crash.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=712536

 modules/engines/pixbuf/pixbuf-rc-style.c |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)
---
diff --git a/modules/engines/pixbuf/pixbuf-rc-style.c b/modules/engines/pixbuf/pixbuf-rc-style.c
index 3597087..46470c2 100644
--- a/modules/engines/pixbuf/pixbuf-rc-style.c
+++ b/modules/engines/pixbuf/pixbuf-rc-style.c
@@ -807,6 +807,27 @@ theme_parse_image(GtkSettings  *settings,
       data->overlay = NULL;
     }
 
+  if (data->gap && !data->gap->filename)
+    {
+      g_scanner_warn (scanner, "Gap image options specified without filename");
+      theme_pixbuf_destroy (data->gap);
+      data->gap = NULL;
+    }
+
+  if (data->gap_start && !data->gap_start->filename)
+    {
+      g_scanner_warn (scanner, "Gap start image options specified without filename");
+      theme_pixbuf_destroy (data->gap_start);
+      data->gap_start = NULL;
+    }
+
+  if (data->gap_end && !data->gap_end->filename)
+    {
+      g_scanner_warn (scanner, "Gap end image options specified without filename");
+      theme_pixbuf_destroy (data->gap_end);
+      data->gap_end = NULL;
+    }
+
   if (token != G_TOKEN_RIGHT_CURLY)
     {
       /* error - cleanup for exit */