diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/testNullToString.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/testNullToString.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,13 @@
+function testNullToString()
+{
+    var a = [];
+    for (var i = 0; i < 10; i++)
+        a.push(String(null));
+    for (i = 0; i < 10; i++) {
+        var t = typeof a[i];
+        if (t != "string")
+           a.push(t);
+    }
+    return a.join(",");
+}
+assertEq(testNullToString(), "null,null,null,null,null,null,null,null,null,null");