--- a/toolkit/components/places/tests/browser/browser_bug248970.js
+++ b/toolkit/components/places/tests/browser/browser_bug248970.js
@@ -25,22 +25,22 @@ add_task(function () {
     windowsToClose.forEach(function(win) {
       win.close();
     });
   });
 
   yield PlacesTestUtils.clearHistory();
 
    // Ensure we wait for the default bookmarks import.
-  let bookmarksDeferred = Promise.defer();
-  waitForCondition(() => {
-    placeItemsCount = getPlacesItemsCount();
-    return placeItemsCount > 0
-  }, bookmarksDeferred.resolve, "Should have default bookmarks");
-  yield bookmarksDeferred.promise;
+  yield new Promise(resolve => {
+    waitForCondition(() => {
+      placeItemsCount = getPlacesItemsCount();
+      return placeItemsCount > 0
+    }, resolve, "Should have default bookmarks")
+  });
 
   // Create a handful of history items with various visit types
   yield PlacesTestUtils.addVisits([
     { uri: visitedURIs[0], transition: TRANSITION_LINK },
     { uri: visitedURIs[1], transition: TRANSITION_TYPED },
     { uri: visitedURIs[2], transition: TRANSITION_BOOKMARK },
     { uri: visitedURIs[3], transition: TRANSITION_REDIRECT_PERMANENT },
     { uri: visitedURIs[4], transition: TRANSITION_REDIRECT_TEMPORARY },
@@ -50,19 +50,19 @@ add_task(function () {
   ]);
 
   placeItemsCount += 7;
   // We added 7 new items to history.
   is(getPlacesItemsCount(), placeItemsCount,
      "Check the total items count");
 
   function* testOnWindow(aIsPrivate, aCount) {
-    let deferred = Promise.defer();
-    whenNewWindowLoaded({ private: aIsPrivate }, deferred.resolve);
-    let win = yield deferred.promise;
+    let win = yield new Promise(resolve => {
+      whenNewWindowLoaded({ private: aIsPrivate }, resolve);
+    });
     windowsToClose.push(win);
 
     // History items should be retrievable by query
     yield checkHistoryItems();
 
     // Updates the place items count
     let count = getPlacesItemsCount();
 

--- a/toolkit/components/places/tests/browser/head.js
+++ b/toolkit/components/places/tests/browser/head.js
@@ -8,20 +8,16 @@ const TRANSITION_REDIRECT_TEMPORARY = Ci
 const TRANSITION_EMBED = Ci.nsINavHistoryService.TRANSITION_EMBED;
 const TRANSITION_FRAMED_LINK = Ci.nsINavHistoryService.TRANSITION_FRAMED_LINK;
 const TRANSITION_DOWNLOAD = Ci.nsINavHistoryService.TRANSITION_DOWNLOAD;
 
 Components.utils.import("resource://gre/modules/NetUtil.jsm");
 
 XPCOMUtils.defineLazyModuleGetter(this, "PlacesTestUtils",
                                   "resource://testing-common/PlacesTestUtils.jsm");
-XPCOMUtils.defineLazyModuleGetter(this, "Promise",
-                                  "resource://gre/modules/Promise.jsm");
-XPCOMUtils.defineLazyModuleGetter(this, "Task",
-                                  "resource://gre/modules/Task.jsm");
 
 /**
  * Returns a moz_places field value for a url.
  *
  * @param aURI
  *        The URI or spec to get field for.
  * param aCallback
  *        Callback function that will get the property value.
@@ -270,47 +266,36 @@ function DBConn(aForceNewConnection) {
       Services.obs.removeObserver(DBCloseCallback, aTopic);
       dbConn.asyncClose();
     }, "profile-before-change", false);
   }
 
   return gDBConn.connectionReady ? gDBConn : null;
 }
 
-function whenDelayedStartupFinished(aWindow, aCallback) {
-  Services.obs.addObserver(function observer(aSubject, aTopic) {
-    if (aWindow == aSubject) {
-      Services.obs.removeObserver(observer, aTopic);
-      executeSoon(function() { aCallback(aWindow); });
-    }
-  }, "browser-delayed-startup-finished", false);
-}
-
 function whenNewWindowLoaded(aOptions, aCallback) {
-  let win = OpenBrowserWindow(aOptions);
-  whenDelayedStartupFinished(win, aCallback);
+  BrowserTestUtils.waitForNewWindow().then(aCallback);
+  OpenBrowserWindow(aOptions);
 }
 
 /**
  * Asynchronously check a url is visited.
  *
  * @param aURI The URI.
  * @param aExpectedValue The expected value.
  * @return {Promise}
  * @resolves When the check has been added successfully.
  * @rejects JavaScript exception.
  */
 function promiseIsURIVisited(aURI, aExpectedValue) {
-  let deferred = Promise.defer();
-
-  PlacesUtils.asyncHistory.isURIVisited(aURI, function(aURI, aIsVisited) {
-    deferred.resolve(aIsVisited);
+  return new Promise(resolve => {
+    PlacesUtils.asyncHistory.isURIVisited(aURI, function(aURI, aIsVisited) {
+      resolve(aIsVisited);
+    });
   });
-
-  return deferred.promise;
 }
 
 function waitForCondition(condition, nextTest, errorMsg) {
   let tries = 0;
   let interval = setInterval(function() {
     if (tries >= 30) {
       ok(false, errorMsg);
       moveOn();