[gtk/a11y/atcontext-realize] a11y: Make the Button labelled by its child label

[Emmanuele Bassi <ebassi src gnome org>]

commit 72415eaa4913568dbb9c0c433949f120a6a246ab
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Wed Nov 4 16:43:59 2020 +0000

    a11y: Make the Button labelled by its child label
    
    Establish the relation whenever we set the label widget.

 gtk/gtkbutton.c | 5 +++++
 1 file changed, 5 insertions(+)
---
diff --git a/gtk/gtkbutton.c b/gtk/gtkbutton.c
index 91023ce39e..f964eb7495 100644
--- a/gtk/gtkbutton.c
+++ b/gtk/gtkbutton.c
@@ -938,6 +938,11 @@ gtk_button_set_icon_name (GtkButton  *button,
       gtk_image_set_from_icon_name (GTK_IMAGE (priv->child), icon_name);
     }
 
+  gtk_accessible_update_relation (GTK_ACCESSIBLE (button),
+                                  GTK_ACCESSIBLE_RELATION_LABELLED_BY,
+                                    g_list_append (NULL, priv->child),
+                                  -1);
+
   gtk_button_set_child_type (button, ICON_CHILD);
   g_object_notify_by_pspec (G_OBJECT (button), props[PROP_ICON_NAME]);
 }