diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_5/extensions/regress-543839.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_5/extensions/regress-543839.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/
+ * Contributor: Igor Bukanov
+ */
+
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 543839;
+var summary = 'js_GetMutableScope caller must lock the object';
+var actual;
+var expect = 1;
+
+printBugNumber(BUGNUMBER);
+printStatus (summary);
+
+jit(true);
+
+function test()
+{
+    jit(true);
+    for (var i = 0; i != 100; ++i)
+        var tmp = { a: 1 };
+    return 1;
+}
+
+if (typeof evalcx == 'undefined')
+{
+    print('Skipping. This test requires evalcx.');
+    actual = expect;
+} else {
+    test();
+    test();
+    test();
+    actual = evalcx("test()", this);
+}
+
+reportCompare(expect, actual, summary);