import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

devtools/shared/defer.js

@@ -0,0 +1,25 @@
+/* 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";
+
+// See bug 1273941 to understand this choice of promise.
+const Promise = require("promise");
+
+/**
+ * Returns a deferred object, with a resolve and reject property.
+ * https://developer.mozilla.org/en-US/docs/Mozilla/JavaScript_code_modules/Promise.jsm/Deferred
+ */
+module.exports = function defer() {
+  let resolve, reject;
+  let promise = new Promise(function () {
+    resolve = arguments[0];
+    reject = arguments[1];
+  });
+  return {
+    resolve: resolve,
+    reject: reject,
+    promise: promise
+  };
+};