[es6] throw TypeError when setting cyclic prototype value

test/mjsunit/harmony/set-prototype-of.js

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 121 matching lines @@
     var object = objects[i];
     Object.preventExtensions(object);
     assertThrows(function() {
       Object.setPrototypeOf(object, proto);
     }, TypeError);
   }
 }
 TestSetPrototypeOfNonExtensibleObject();
 
 
+function TestSetPrototypeCyclic() {
+  var objects = [
+    Object.prototype, {},
+    Array.prototype, [],
+    Error.prototype, new TypeError,
+    // etc ...
+  ];
+  for (var i = 0; i < objects.length; i += 2) {
+    var object = objects[i];
+    var value = objects[i+1];
+    assertThrows(function() {
+      Object.setPrototypeOf(object, value);

[mike4, 2015/06/19 16:43:12]

How about a second assertion for `object.__proto__ = value`? At first I thought
this might need to go somewhere else, but it doesn't look like the mjsunit suite
makes any distinction for Annex B functionality.

[caitp (gmail), 2015/06/19 17:05:36]

Done.

+    }, TypeError);
+  }
+}
+TestSetPrototypeCyclic();
+
+
 function TestLookup() {
   var object = {};
   assertFalse('x' in object);
   assertFalse('y' in object);
 
   var oldProto = {
     x: 'old x',
     y: 'old y'
   };
   Object.setPrototypeOf(object, oldProto);
   assertEquals(object.x, 'old x');
   assertEquals(object.y, 'old y');
 
   var newProto = {
     x: 'new x'
   };
   Object.setPrototypeOf(object, newProto);
   assertEquals(object.x, 'new x');
   assertFalse('y' in object);
 }
 TestLookup();