diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/bug559912.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/bug559912.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,12 @@
+
+function s(f) { this._m = f; }
+function C() {
+    Object.defineProperty(this, "m", {set: s});
+    this.m = function () {};
+}
+var last = {};
+for (var i = 0; i < 20; i++) {
+  var a = new C;
+  assertEq(a._m === last._m, false);
+  last = a;
+}