add alias tests

Author: withinboredom

tests/classes/inner_classes/aliases.phpt

@@ -0,0 +1,18 @@
+--TEST--
+aliases cannot escape
+--FILE--
+<?php
+
+class Outer {
+    private class Inner {}
+}
+
+class_alias(Outer\Inner::class, 'InnerAlias');
+
+new InnerAlias();
+?>
+--EXPECTF--
+Fatal error: Uncaught TypeError: Cannot instantiate class Outer\Inner from the global scope in %s:%d
+Stack trace:
+#0 {main}
+  thrown in %s on line %d