diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/gc/bug-975959.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/gc/bug-975959.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,20 @@
+if (!getBuildConfiguration().parallelJS)
+  quit(0);
+
+try {
+    y = z = [];
+    y[1] = x
+    for (var e, x = [];; d) {}
+} catch (e) {}
+try {
+    Object.defineProperty(this, "y", {
+        get: function() {
+            z.filterPar(function() {})
+        }
+    })(1 instanceof 2)
+} catch (e) {}
+y
+verifyprebarriers()
+y
+verifyprebarriers()
+y