diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/for-of/semantics-01.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/for-of/semantics-01.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,13 @@
+// for-of is defined in terms of basic operations on objects, particularly
+// [[Get]] for properties named "iterator" and "next", and [[Call]]. These
+// "semantics" tests check that for-of really does appear to be implemented in
+// terms of those more basic operations, as required by the spec, even in
+// unusual cases.
+
+// Deleting Array.prototype.iterator makes for-of stop working on arrays.
+
+load(libdir + "asserts.js");
+load(libdir + "iteration.js");
+
+delete Array.prototype[std_iterator];
+assertThrowsInstanceOf(function () { for (var x of []) ; }, TypeError);