[gtk] a11y tests: Update stack ui file

[Matthias Clasen <matthiasc src gnome org>]

commit f05932811bfb484665cbc6c0e297b60c78a99a04
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Feb 8 09:29:01 2019 -0500

    a11y tests: Update stack ui file
    
    The conversion was done with gtk-builder-tool simplify --3to4.

 testsuite/a11y/stack.ui | 32 ++++++++++++++------------------
 1 file changed, 14 insertions(+), 18 deletions(-)
---
diff --git a/testsuite/a11y/stack.ui b/testsuite/a11y/stack.ui
index 9b8ee38406..2ce89fd034 100644
--- a/testsuite/a11y/stack.ui
+++ b/testsuite/a11y/stack.ui
@@ -1,40 +1,36 @@
-<?xml version="1.0" encoding="UTF-8"?>
 <interface>
-  <!-- interface-requires gtk+ 3.0 -->
   <object class="GtkWindow" id="window1">
-    <property name="can_focus">False</property>
     <property name="type">popup</property>
     <child>
       <object class="GtkBox" id="box1">
-        <property name="visible">True</property>
         <child>
           <object class="GtkStackSwitcher" id="stackswitcher1">
-            <property name="visible">True</property>
             <property name="stack">stack1</property>
           </object>
         </child>
         <child>
           <object class="GtkStack" id="stack1">
-            <property name="visible">True</property>
             <child>
-              <object class="GtkButton" id="page1">
-                <property name="label" translatable="yes">Yes</property>
-                <property name="visible">True</property>
-              </object>
-              <packing>
+              <object class="GtkStackPage">
                 <property name="name">page1</property>
                 <property name="title">Page 1</property>
-              </packing>
+                <property name="child">
+                  <object class="GtkButton" id="page1">
+                    <property name="label" translatable="yes">Yes</property>
+                  </object>
+                </property>
+              </object>
             </child>
             <child>
-              <object class="GtkButton" id="page2">
-                <property name="label" translatable="yes">No</property>
-                <property name="visible">True</property>
-              </object>
-              <packing>
+              <object class="GtkStackPage">
                 <property name="name">page2</property>
                 <property name="title">Page 2</property>
-              </packing>
+                <property name="child">
+                  <object class="GtkButton" id="page2">
+                    <property name="label" translatable="yes">No</property>
+                  </object>
+                </property>
+              </object>
             </child>
           </object>
         </child>