[glib] gtype: Fast-path for g_type_is_a

[Edward Hervey <edwardrv src gnome org>]

commit 3e2735f4680b9f46548e7d039b0241cd24aee162
Author: Edward Hervey <bilboed bilboed com>
Date:   Mon Jun 23 11:39:04 2014 +0200

    gtype: Fast-path for g_type_is_a
    
    Do I really need to explain why ?
    
    https://bugzilla.gnome.org/show_bug.cgi?id=732085

 gobject/gtype.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gobject/gtype.c b/gobject/gtype.c
index f766ffd..dff5b4a 100644
--- a/gobject/gtype.c
+++ b/gobject/gtype.c
@@ -3499,6 +3499,9 @@ g_type_is_a (GType type,
 {
   TypeNode *node, *iface_node;
   gboolean is_a;
+
+  if (type == iface_type)
+    return TRUE;
   
   node = lookup_type_node_I (type);
   iface_node = lookup_type_node_I (iface_type);