[gtk/wip/matthiasc/opbuffer] Fix a crash with glyph caching

[Matthias Clasen <matthiasc src gnome org>]

commit d777300d4e4536fa12c5a82c370061d024a9baee
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Oct 15 22:52:28 2019 -0400

    Fix a crash with glyph caching
    
    We need to treat atlas-less cached glyphs like
    atlases, when it comes to invalidating text node
    render data.

 gsk/gl/gskglglyphcache.c | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/gsk/gl/gskglglyphcache.c b/gsk/gl/gskglglyphcache.c
index 5571293ee5..80216ab5be 100644
--- a/gsk/gl/gskglglyphcache.c
+++ b/gsk/gl/gskglglyphcache.c
@@ -362,6 +362,12 @@ gsk_gl_glyph_cache_begin_frame (GskGLGlyphCache *self,
                 {
                   gsk_gl_driver_destroy_texture (driver, value->texture_id);
                   g_hash_table_iter_remove (&iter);
+
+                  /* Sadly, if we drop an atlas-less cached glyph, we
+                   * have to treat it like a dropped atlas and purge
+                   * text node render data.
+                   */
+                  self->atlas_timestamp++;
                 }
             }
           else