// Setting a "new" prototype to the current [[Prototype]] value should never fail var x = {}, t = Object.create(x); Object.preventExtensions(t); // Should not fail, because it is the same [[Prototype]] value Object.setPrototypeOf(t, x); // Object.prototype's [[Prototype]] is immutable, make sure we can still set null Object.setPrototypeOf(Object.prototype, null); reportCompare(true, true);