macOS Accessibility: don't create an unnecessary interface

We only need to compare elements to determine whether this element has
focus.

Task-number: QTBUG-34337
Pick-to: 6.5
Change-Id: Ic1388ac00381735acfbf1e5877a658f4bd534dfb
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

src/plugins/platforms/cocoa/qcocoaaccessibilityelement.mm

@@ -249,12 +249,9 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
 
 - (BOOL)isAccessibilityFocused
 {
-    if (QAccessibleInterface *iface = self.qtInterface) {
-        // Just check if the app thinks we're focused.
-        id focusedElement = NSApp.accessibilityApplicationFocusedUIElement;
-        return [focusedElement isEqual:self];
-    }
-    return false;
+    // Just check if the app thinks we're focused.
+    id focusedElement = NSApp.accessibilityApplicationFocusedUIElement;
+    return [focusedElement isEqual:self];
 }
 
 // attributes