[gtk/gtk-3-24: 1/2] GtkCssImageSurface: Plug cache surface leak

[Matthias Clasen <matthiasc src gnome org>]

commit 7e2bebb4d503ed0d519a64bb653f94b6e9ef004d
Author: Sebastian Keller <skeller src gnome org>
Date:   Mon Jan 13 23:24:47 2020 +0100

    GtkCssImageSurface: Plug cache surface leak
    
    Fixes https://gitlab.gnome.org/GNOME/gtk/issues/2373

 gtk/gtkcssimagesurface.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/gtk/gtkcssimagesurface.c b/gtk/gtkcssimagesurface.c
index f6f694aff7..a8fd150d08 100644
--- a/gtk/gtkcssimagesurface.c
+++ b/gtk/gtkcssimagesurface.c
@@ -140,6 +140,8 @@ gtk_css_image_surface_dispose (GObject *object)
       surface->surface = NULL;
     }
 
+  g_clear_pointer (&surface->cache, cairo_surface_destroy);
+
   G_OBJECT_CLASS (_gtk_css_image_surface_parent_class)->dispose (object);
 }