Accessibility: Fix crash when accessing accessible children.

The window would create new child interfaces every time
it's children are queried. Instead properly use the
crash.

Task-number: QTBUG-31417
Change-Id: Ifc7bbdbdb9a506fe04a348fba643f1d52a6157e7
Reviewed-by: Jan Arve Sæther <jan-arve.saether@digia.com>

src/plugins/accessible/quick/qaccessiblequickview.cpp

@@ -81,10 +81,8 @@ QAccessibleInterface *QAccessibleQuickWindow::parent() const
 
 QAccessibleInterface *QAccessibleQuickWindow::child(int index) const
 {
-    if (index == 0) {
-        if (QQuickItem *declarativeRoot = rootItem())
-            return new QAccessibleQuickItem(declarativeRoot);
-    }
+    if (index == 0)
+        return QAccessible::queryAccessibleInterface(rootItem());
     return 0;
 }