diff -r 000000000000 -r 6474c204b198 addon-sdk/source/lib/sdk/l10n/json/core.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/addon-sdk/source/lib/sdk/l10n/json/core.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,35 @@
+/* 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"
+};
+
+let usingJSON = false;
+let hash = {}, bestMatchingLocale = null;
+try {
+  let data = require("@l10n/data");
+  hash = data.hash;
+  bestMatchingLocale = data.bestMatchingLocale;
+  usingJSON = true;
+}
+catch(e) {}
+
+exports.usingJSON = usingJSON;
+
+// Returns the translation for a given key, if available.
+exports.get = function get(k) {
+  return k in hash ? hash[k] : null;
+}
+
+// Returns the full length locale code: ja-JP-mac, en-US or fr
+exports.locale = function locale() {
+  return bestMatchingLocale;
+}
+// Returns the short locale code: ja, en, fr
+exports.language = function language() {
+  return bestMatchingLocale ? bestMatchingLocale.split("-")[0].toLowerCase()
+                            : null;
+}