[gtk] rendernode: Add missing return

[Benjamin Otte <otte src gnome org>]

commit 1792f3b21efbd8fe04cf49f2b1b9f731e8c191ca
Author: Benjamin Otte <otte redhat com>
Date:   Thu Apr 5 17:32:57 2018 +0200

    rendernode: Add missing return
    
    Don't to extra work when not needed.

 gsk/gskrendernodeimpl.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/gsk/gskrendernodeimpl.c b/gsk/gskrendernodeimpl.c
index 59681c888c..36c99376ba 100644
--- a/gsk/gskrendernodeimpl.c
+++ b/gsk/gskrendernodeimpl.c
@@ -4278,6 +4278,7 @@ gsk_cross_fade_node_diff (GskRenderNode  *node1,
     {
       gsk_render_node_diff (self1->start, self2->start, region);
       gsk_render_node_diff (self1->end, self2->end, region);
+      return;
     }
 
   gsk_render_node_diff_impossible (node1, node2, region);