Fix regression preventing VoiceOver following the keyboard focus

In fafdb17 a potential nullptr deref
was fixed, but it changed the hierarchy of accessible objects.
The new hierarchy would prefer to send a parent object that represents
the application, but macOS needs the window to be in the hierarchy for
VoiceOver to behave as expected.
Tweak it so that we give the window as parent again, not the app.

Change-Id: I5f7f59b07d0966c8bcf96968e4ed65eba9e05be6
Reviewed-by: Jan Arve Sæther <[email protected]>

src/plugins/platforms/cocoa/qcocoaaccessibilityelement.mm

@@ -235,9 +235,16 @@ - (id)parentElement {
     if (!iface || !iface->isValid())
         return nil;
 
+    // macOS expects that the hierarchy is:
+    // App -> Window -> Children
+    // We don't actually have the window reflected properly in QAccessibility.
+    // Check if the parent is the application and then instead return the native window.
+
     if (QAccessibleInterface *parent = iface->parent()) {
-        QAccessible::Id parentId = QAccessible::uniqueId(parent);
-        return [QMacAccessibilityElement elementWithId: parentId];
+        if (parent->role() != QAccessible::Application) {
+            QAccessible::Id parentId = QAccessible::uniqueId(parent);
+            return [QMacAccessibilityElement elementWithId: parentId];
+        }
     }
 
     if (QWindow *window = iface->window()) {