Convert GailExpander to GtkExpanderAccessible

At the same time, drop the AtkText implementation.
Also, reintroduce a GtkBoxAccessible, since the previous
way of setting the role in get_accessible was affecting
GtkBox subclasses negatively.

Adjust expected test output to match.

gtk/a11y/gtkboxaccessible.c

@@ -0,0 +1,46 @@
+/* GAIL - The GNOME Accessibility Implementation Library
+ * Copyright 2004 Sun Microsystems Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "config.h"
+
+#include <gtk/gtk.h>
+#include "gtkboxaccessible.h"
+
+G_DEFINE_TYPE (GtkBoxAccessible, gtk_box_accessible, GAIL_TYPE_CONTAINER)
+
+static void
+gtk_box_accessible_initialize (AtkObject *accessible,
+                               gpointer   data)
+{
+  ATK_OBJECT_CLASS (gtk_box_accessible_parent_class)->initialize (accessible, data);
+  accessible->role = ATK_ROLE_FILLER;
+}
+
+static void
+gtk_box_accessible_class_init (GtkBoxAccessibleClass *klass)
+{
+  AtkObjectClass *class = ATK_OBJECT_CLASS (klass);
+
+  class->initialize = gtk_box_accessible_initialize;
+}
+
+static void
+gtk_box_accessible_init (GtkBoxAccessible *scale)
+{
+}