vulkan: Handle empty rects in intersects_rect()

Apart from the none case, this was already handled, so we just check if
the rect is empty now.

gsk/vulkan/gskvulkanclip.c

@@ -252,7 +252,7 @@ gsk_vulkan_clip_intersects_rect (const GskVulkanClip    *self,
       return FALSE;
 
     case GSK_VULKAN_CLIP_NONE:
-      return TRUE;
+      return r.size.width > 0 && r.size.height > 0;
 
     case GSK_VULKAN_CLIP_RECT:
       return graphene_rect_intersection (&self->rect.bounds, &r, NULL);