[gtk] gsk: Remove some unused defines

[Timm Bäder <baedert src gnome org>]

commit 05b9a996616d2b2c95c0a191fbfcdd2bc9a9bbec
Author: Timm Bäder <mail baedert org>
Date:   Sun Jan 26 17:39:26 2020 +0100

    gsk: Remove some unused defines
    
    These are from the GVariant days of render nodes.

 gsk/gskrendernode.c | 3 ---
 1 file changed, 3 deletions(-)
---
diff --git a/gsk/gskrendernode.c b/gsk/gskrendernode.c
index 9646049da4..366ecfdb99 100644
--- a/gsk/gskrendernode.c
+++ b/gsk/gskrendernode.c
@@ -314,9 +314,6 @@ gsk_render_node_diff (GskRenderNode  *node1,
   return node1->node_class->diff (node1, node2, region);
 }
 
-#define GSK_RENDER_NODE_SERIALIZATION_VERSION 0
-#define GSK_RENDER_NODE_SERIALIZATION_ID "GskRenderNode"
-
 /**
  * gsk_render_node_write_to_file:
  * @node: a #GskRenderNode