[gtk+] gsk: Fix pre-condition check

[Emmanuele Bassi <ebassi src gnome org>]

commit 9c86579e4700fededcbeddc3eccb3be099fcbcfb
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Fri Jul 8 16:24:35 2016 +0100

    gsk: Fix pre-condition check
    
    We warn if the node is marked as not mutable.

 gsk/gskrendernode.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gsk/gskrendernode.c b/gsk/gskrendernode.c
index 5f16bfd..93bd2dd 100644
--- a/gsk/gskrendernode.c
+++ b/gsk/gskrendernode.c
@@ -1268,7 +1268,7 @@ gsk_render_node_set_blend_mode (GskRenderNode *node,
                                 GskBlendMode   blend_mode)
 {
   g_return_if_fail (GSK_IS_RENDER_NODE (node));
-  g_return_if_fail (!node->is_mutable);
+  g_return_if_fail (node->is_mutable);
 
   if (node->blend_mode == blend_mode)
     return;