diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/proxy/testDirectProxyValidateProperty6.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/proxy/testDirectProxyValidateProperty6.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,28 @@
+load(libdir + "asserts.js");
+
+/*
+ * Throw a TypeError if both the current descriptor and the descriptor returned
+ * by the trap are accessor descriptors, the current descriptor is
+ * non-configurable, and the descriptor returned by the trap has a different
+ * setter.
+ */
+var target = {};
+Object.defineProperty(target, 'foo', {
+    set: function (value) {i
+        target.foo = 'bar';
+    },
+    configurable: false
+});
+var caught = false;
+assertThrowsInstanceOf(function () { 
+    Object.getOwnPropertyDescriptor(new Proxy(target, {
+        getOwnPropertyDescriptor: function (target, name) {
+            return {
+                set: function (value) {
+                    target.foo = 'baz';
+                },
+                configurable: false
+            };
+        }
+    }), 'foo');
+}, TypeError);