[gtk] gl renderer: Fix inverted dy in inset shadows

[Timm Bäder <baedert src gnome org>]

commit b9726901a576e68914d0802a3d431b7bbf20711a
Author: Timm Bäder <mail baedert org>
Date:   Sun Dec 29 16:43:51 2019 +0100

    gl renderer: Fix inverted dy in inset shadows

 gsk/gl/gskglrenderer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gsk/gl/gskglrenderer.c b/gsk/gl/gskglrenderer.c
index d9fa0e9a98..a1d100a3db 100644
--- a/gsk/gl/gskglrenderer.c
+++ b/gsk/gl/gskglrenderer.c
@@ -1602,7 +1602,7 @@ render_inset_shadow_node (GskGLRenderer   *self,
       op->outline = transform_rect (self, builder, &outline_to_blur);
       op->spread = spread * scale;
       op->offset[0] = dx * scale;
-      op->offset[1] = -dy * scale;
+      op->offset[1] = dy * scale;
 
       ops_draw (builder, (GskQuadVertex[GL_N_VERTICES]) {
         { { 0,             0              }, { 0, 1 }, },