diff -r 000000000000 -r 6474c204b198 addon-sdk/source/lib/sdk/system/runtime.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/addon-sdk/source/lib/sdk/system/runtime.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,27 @@
+/* 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/. */
+
+"use strict";
+
+module.metadata = {
+  "stability": "unstable"
+};
+
+const { Cc, Ci } = require("chrome");
+const runtime = Cc["@mozilla.org/xre/app-info;1"].getService(Ci.nsIXULRuntime);
+
+exports.inSafeMode = runtime.inSafeMode;
+exports.OS = runtime.OS;
+exports.processType = runtime.processType;
+exports.widgetToolkit = runtime.widgetToolkit;
+
+// Attempt to access `XPCOMABI` may throw exception, in which case exported
+// `XPCOMABI` will be set to `null`.
+// https://mxr.mozilla.org/mozilla-central/source/toolkit/xre/nsAppRunner.cpp#732
+try {
+  exports.XPCOMABI = runtime.XPCOMABI;
+}
+catch (error) {
+  exports.XPCOMABI = null;
+}