Add test for bug #60161

This has been fixed in PHP 7.4, let's make sure it stays fixed.

Author: nikic

Zend/tests/bug60161.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Bug #60161: Implementing an interface extending Traversable is order dependent
+--FILE--
+<?php
+
+interface Foo extends Traversable {
+}
+
+class Example implements Foo, IteratorAggregate {
+    public function getIterator() {
+        return new ArrayIterator([]);
+    }
+}
+
+?>
+===DONE===
+--EXPECT--
+===DONE===