[gtk] gl renderer: Skip invisible shadows

[Timm Bäder <baedert src gnome org>]

commit ccb987753407251c6be7be1b4d2d9198684700fa
Author: Timm Bäder <mail baedert org>
Date:   Sat May 18 09:11:59 2019 +0200

    gl renderer: Skip invisible shadows

 gsk/gl/gskglrenderer.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/gsk/gl/gskglrenderer.c b/gsk/gl/gskglrenderer.c
index b37c36afaa..9aa2df3199 100644
--- a/gsk/gl/gskglrenderer.c
+++ b/gsk/gl/gskglrenderer.c
@@ -1807,6 +1807,9 @@ render_shadow_node (GskGLRenderer       *self,
           continue;
         }
 
+      if (gdk_rgba_is_clear (&shadow->color))
+        continue;
+
       min_x = builder->dx + shadow_child->bounds.origin.x;
       min_y = builder->dy + shadow_child->bounds.origin.y;
       max_x = min_x + shadow_child->bounds.size.width;