[es6] throw TypeError when setting cyclic prototype value

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

Index: test/mjsunit/harmony/set-prototype-of.js
diff --git a/test/mjsunit/harmony/set-prototype-of.js b/test/mjsunit/harmony/set-prototype-of.js
index e06215a0edfcca65a84b4524f017c9805e856d22..c786f5420f93648475e367ac08bcddab064824c0 100644
--- a/test/mjsunit/harmony/set-prototype-of.js
+++ b/test/mjsunit/harmony/set-prototype-of.js
@@ -139,6 +139,24 @@ function TestSetPrototypeOfNonExtensibleObject() {
 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);