--- a/browser/modules/test/browser/browser_BrowserErrorReporter.js
+++ b/browser/modules/test/browser/browser_BrowserErrorReporter.js
@@ -1,16 +1,14 @@
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/ */
 "use strict";
 
 ChromeUtils.import("resource:///modules/BrowserErrorReporter.jsm", this);
 
-Cu.importGlobalProperties(["fetch"]);
-
 /* global sinon */
 Services.scriptloader.loadSubScript("resource://testing-common/sinon-2.3.2.js");
 registerCleanupFunction(function() {
   delete window.sinon;
 });
 
 const PREF_ENABLED = "browser.chrome.errorReporter.enabled";
 const PREF_PROJECT_ID = "browser.chrome.errorReporter.projectId";

--- a/browser/modules/test/browser/browser_ContentSearch.js
+++ b/browser/modules/test/browser/browser_ContentSearch.js
@@ -1,18 +1,16 @@
 /* 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/. */
 
 const TEST_MSG = "ContentSearchTest";
 const CONTENT_SEARCH_MSG = "ContentSearch";
 const TEST_CONTENT_SCRIPT_BASENAME = "contentSearch.js";
 
-Cu.importGlobalProperties(["XMLHttpRequest"]);
-
 var gMsgMan;
 /* import-globals-from ../../../components/search/test/head.js */
 Services.scriptloader.loadSubScript(
   "chrome://mochitests/content/browser/browser/components/search/test/head.js",
   this);
 
 let originalEngine = Services.search.currentEngine;
 

--- a/toolkit/components/extensions/test/browser/browser_ext_themes_toolbarbutton_colors.js
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_toolbarbutton_colors.js
@@ -1,11 +1,11 @@
 "use strict";
 
-Cu.importGlobalProperties(["InspectorUtils"]);
+/* globals InspectorUtils */
 
 // This test checks whether applied WebExtension themes that attempt to change
 // the button background color properties are applied correctly.
 
 add_task(async function test_button_background_properties() {
   const BUTTON_BACKGROUND_ACTIVE = "#FFFFFF";
   const BUTTON_BACKGROUND_HOVER = "#59CBE8";
 

--- a/toolkit/components/thumbnails/test/browser_thumbnails_expiration.js
+++ b/toolkit/components/thumbnails/test/browser_thumbnails_expiration.js
@@ -1,17 +1,17 @@
 /* Any copyright is dedicated to the Public Domain.
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
 const URL = "http://mochi.test:8888/?t=" + Date.now();
 const URL1 = URL + "#1";
 const URL2 = URL + "#2";
 const URL3 = URL + "#3";
 
-var tmp = {};
+var tmp = Cu.Sandbox(window, {wantGlobalProperties: ["ChromeUtils"]});
 Services.scriptloader.loadSubScript("resource://gre/modules/PageThumbs.jsm", tmp);
 
 const EXPIRATION_MIN_CHUNK_SIZE = 50;
 const {PageThumbsExpiration} = tmp;
 
 function* runTests() {
   // Create dummy URLs.
   let dummyURLs = [];

--- a/toolkit/components/thumbnails/test/browser_thumbnails_storage_migrate3.js
+++ b/toolkit/components/thumbnails/test/browser_thumbnails_storage_migrate3.js
@@ -2,17 +2,17 @@
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
 const URL = "http://mochi.test:8888/migration3";
 const URL2 = URL + "#2";
 const URL3 = URL + "#3";
 const THUMBNAIL_DIRECTORY = "thumbnails";
 const PREF_STORAGE_VERSION = "browser.pagethumbnails.storage_version";
 
-var tmp = {};
+var tmp = Cu.Sandbox(window, {wantGlobalProperties: ["ChromeUtils"]});
 Services.scriptloader.loadSubScript("resource://gre/modules/PageThumbs.jsm", tmp);
 var {PageThumbsStorageMigrator} = tmp;
 
 XPCOMUtils.defineLazyServiceGetter(this, "gDirSvc",
   "@mozilla.org/file/directory_service;1", "nsIProperties");
 
 /**
  * This test makes sure we correctly migrate to thumbnail storage version 3.

--- a/toolkit/modules/tests/browser/browser_WebRequest_ancestors.js
+++ b/toolkit/modules/tests/browser/browser_WebRequest_ancestors.js
@@ -1,11 +1,13 @@
 "use strict";
 
-Cu.importGlobalProperties(["XMLHttpRequest"]);
+// This test requires an XMLHttpRequest constructor which isn't
+// associated with a window.
+const {XMLHttpRequest} = Cu.Sandbox(window, {wantGlobalProperties: ["XMLHttpRequest"]});
 
 var {WebRequest} = ChromeUtils.import("resource://gre/modules/WebRequest.jsm", {});
 var {PromiseUtils} = ChromeUtils.import("resource://gre/modules/PromiseUtils.jsm", {});
 
 add_task(async function test_ancestors_exist() {
   let deferred = PromiseUtils.defer();
   function onBeforeRequest(details) {
     info(`onBeforeRequest ${details.url}`);