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diff --git a/toolkit/jetpack/sdk/dom/events.js b/toolkit/jetpack/sdk/dom/events.js
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+++ b/toolkit/jetpack/sdk/dom/events.js
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+/* 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 { Cu } = require("chrome");
+const { ShimWaiver } = Cu.import("resource://gre/modules/ShimWaiver.jsm");
+
+// Utility function that returns copy of the given `text` with last character
+// removed if it is `"s"`.
+function singularify(text) {
+  return text[text.length - 1] === "s" ? text.substr(0, text.length - 1) : text;
+}
+
+// Utility function that takes event type, argument is passed to
+// `document.createEvent` and returns name of the initializer method of the
+// given event. Please note that there are some event types whose initializer
+// methods can't be guessed by this function. For more details see following
+// link: https://developer.mozilla.org/En/DOM/Document.createEvent
+function getInitializerName(category) {
+  return "init" + singularify(category);
+}
+
+/**
+ * Registers an event `listener` on a given `element`, that will be called
+ * when events of specified `type` is dispatched on the `element`.
+ * @param {Element} element
+ *    Dom element to register listener on.
+ * @param {String} type
+ *    A string representing the
+ *    [event type](https://developer.mozilla.org/en/DOM/event.type) to
+ *    listen for.
+ * @param {Function} listener
+ *    Function that is called whenever an event of the specified `type`
+ *    occurs.
+ * @param {Boolean} capture
+ *    If true, indicates that the user wishes to initiate capture. After
+ *    initiating capture, all events of the specified type will be dispatched
+ *    to the registered listener before being dispatched to any `EventTarget`s
+ *    beneath it in the DOM tree. Events which are bubbling upward through
+ *    the tree will not trigger a listener designated to use capture.
+ *    See [DOM Level 3 Events](http://www.w3.org/TR/DOM-Level-3-Events/#event-flow)
+ *    for a detailed explanation.
+ */
+function on(element, type, listener, capture, shimmed = false) {
+  // `capture` defaults to `false`.
+  capture = capture || false;
+  if (shimmed) {
+    element.addEventListener(type, listener, capture);
+  } else {
+    ShimWaiver.getProperty(element, "addEventListener")(type, listener, capture);
+  }
+}
+exports.on = on;
+
+/**
+ * Registers an event `listener` on a given `element`, that will be called
+ * only once, next time event of specified `type` is dispatched on the
+ * `element`.
+ * @param {Element} element
+ *    Dom element to register listener on.
+ * @param {String} type
+ *    A string representing the
+ *    [event type](https://developer.mozilla.org/en/DOM/event.type) to
+ *    listen for.
+ * @param {Function} listener
+ *    Function that is called whenever an event of the specified `type`
+ *    occurs.
+ * @param {Boolean} capture
+ *    If true, indicates that the user wishes to initiate capture. After
+ *    initiating capture, all events of the specified type will be dispatched
+ *    to the registered listener before being dispatched to any `EventTarget`s
+ *    beneath it in the DOM tree. Events which are bubbling upward through
+ *    the tree will not trigger a listener designated to use capture.
+ *    See [DOM Level 3 Events](http://www.w3.org/TR/DOM-Level-3-Events/#event-flow)
+ *    for a detailed explanation.
+ */
+function once(element, type, listener, capture, shimmed = false) {
+  on(element, type, function selfRemovableListener(event) {
+    removeListener(element, type, selfRemovableListener, capture, shimmed);
+    listener.apply(this, arguments);
+  }, capture, shimmed);
+}
+exports.once = once;
+
+/**
+ * Unregisters an event `listener` on a given `element` for the events of the
+ * specified `type`.
+ *
+ * @param {Element} element
+ *    Dom element to unregister listener from.
+ * @param {String} type
+ *    A string representing the
+ *    [event type](https://developer.mozilla.org/en/DOM/event.type) to
+ *    listen for.
+ * @param {Function} listener
+ *    Function that is called whenever an event of the specified `type`
+ *    occurs.
+ * @param {Boolean} capture
+ *    If true, indicates that the user wishes to initiate capture. After
+ *    initiating capture, all events of the specified type will be dispatched
+ *    to the registered listener before being dispatched to any `EventTarget`s
+ *    beneath it in the DOM tree. Events which are bubbling upward through
+ *    the tree will not trigger a listener designated to use capture.
+ *    See [DOM Level 3 Events](http://www.w3.org/TR/DOM-Level-3-Events/#event-flow)
+ *    for a detailed explanation.
+ */
+function removeListener(element, type, listener, capture, shimmed = false) {
+  if (shimmed) {
+    element.removeEventListener(type, listener, capture);
+  } else {
+    ShimWaiver.getProperty(element, "removeEventListener")(type, listener, capture);
+  }
+}
+exports.removeListener = removeListener;
+
+/**
+ * Emits event of the specified `type` and `category` on the given `element`.
+ * Specified `settings` are used to initialize event before dispatching it.
+ * @param {Element} element
+ *    Dom element to dispatch event on.
+ * @param {String} type
+ *    A string representing the
+ *    [event type](https://developer.mozilla.org/en/DOM/event.type).
+ * @param {Object} options
+ *    Options object containing following properties:
+ *    - `category`: String passed to the `document.createEvent`. Option is
+ *      optional and defaults to "UIEvents".
+ *    - `initializer`: If passed it will be used as name of the method used
+ *      to initialize event. If omitted name will be generated from the
+ *      `category` field by prefixing it with `"init"` and removing last
+ *      character if it matches `"s"`.
+ *    - `settings`: Array of settings that are forwarded to the event
+ *      initializer after firs `type` argument.
+ * @see https://developer.mozilla.org/En/DOM/Document.createEvent
+ */
+function emit(element, type, { category, initializer, settings }, shimmed = false) {
+  category = category || "UIEvents";
+  initializer = initializer || getInitializerName(category);
+  let document = element.ownerDocument;
+  let event = document.createEvent(category);
+  event[initializer].apply(event, [type].concat(settings));
+  if (shimmed) {
+    element.dispatchEvent(event);
+  } else {
+    ShimWaiver.getProperty(element, "dispatchEvent")(event);
+  }
+};
+exports.emit = emit;
+
+// Takes DOM `element` and returns promise which is resolved
+// when given element is removed from it's parent node.
+const removed = element => {
+  return new Promise(resolve => {
+    const { MutationObserver } = element.ownerDocument.defaultView;
+    const observer = new MutationObserver(mutations => {
+      for (let mutation of mutations) {
+        for (let node of mutation.removedNodes || []) {
+          if (node === element) {
+            observer.disconnect();
+            resolve(element);
+          }
+        }
+      }
+    });
+    observer.observe(element.parentNode, {childList: true});
+  });
+};
+exports.removed = removed;
+
+const when = (element, eventName, capture=false, shimmed=false) => new Promise(resolve => {
+  const listener = event => {
+    if (shimmed) {
+      element.removeEventListener(eventName, listener, capture);
+    } else {
+      ShimWaiver.getProperty(element, "removeEventListener")(eventName, listener, capture);
+    }
+    resolve(event);
+  };
+
+  if (shimmed) {
+    element.addEventListener(eventName, listener, capture);
+  } else {
+    ShimWaiver.getProperty(element, "addEventListener")(eventName, listener, capture);
+  }
+});
+exports.when = when;