[gtk+] rendernodeimpl: Fix a crash

[Timm Bäder <baedert src gnome org>]

commit 5e7b3030b913b82ddd9e54d49028b0c6dce75211
Author: Timm Bäder <mail baedert org>
Date:   Wed Jan 17 21:47:05 2018 +0100

    rendernodeimpl: Fix a crash
    
    We may get a NULL renderer here.

 gsk/gskrendernodeimpl.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gsk/gskrendernodeimpl.c b/gsk/gskrendernodeimpl.c
index f78226c..3998288 100644
--- a/gsk/gskrendernodeimpl.c
+++ b/gsk/gskrendernodeimpl.c
@@ -1953,7 +1953,7 @@ gsk_cairo_node_get_draw_context (GskRenderNode *node,
                    node->bounds.size.width, node->bounds.size.height);
   cairo_clip (res);
 
-  if (GSK_RENDERER_DEBUG_CHECK (renderer, SURFACE))
+  if (renderer && GSK_RENDERER_DEBUG_CHECK (renderer, SURFACE))
     {
       const char *prefix;
       prefix = g_getenv ("GSK_DEBUG_PREFIX");