diff -r 000000000000 -r 6474c204b198 js/src/vm/Monitor.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/vm/Monitor.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "vm/Monitor.h"
+
+using namespace js;
+
+bool
+Monitor::init()
+{
+#ifdef JS_THREADSAFE
+    lock_ = PR_NewLock();
+    if (!lock_)
+        return false;
+
+    condVar_ = PR_NewCondVar(lock_);
+    if (!condVar_)
+        return false;
+#endif
+
+    return true;
+}