--- a/browser/base/content/test/general/browser_bug623893.js
+++ b/browser/base/content/test/general/browser_bug623893.js
@@ -1,45 +1,37 @@
-function test() {
-  waitForExplicitFinish();
+add_task(function* test() {
+  yield BrowserTestUtils.withNewTab("data:text/plain;charset=utf-8,1", function* (browser) {
+    BrowserTestUtils.loadURI(browser, "data:text/plain;charset=utf-8,2");
+    yield BrowserTestUtils.browserLoaded(browser);
+
+    BrowserTestUtils.loadURI(browser, "data:text/plain;charset=utf-8,3");
+    yield BrowserTestUtils.browserLoaded(browser);
+
+    yield duplicate(0, "maintained the original index");
+    yield BrowserTestUtils.removeTab(gBrowser.selectedTab);
 
-  loadAndWait("data:text/plain,1", function() {
-    loadAndWait("data:text/plain,2", function() {
-      loadAndWait("data:text/plain,3", runTests);
-    });
+    yield duplicate(-1, "went back");
+    yield duplicate(1, "went forward");
+    yield BrowserTestUtils.removeTab(gBrowser.selectedTab);
+    yield BrowserTestUtils.removeTab(gBrowser.selectedTab);
+  });
+});
+
+function promiseGetIndex(browser) {
+  return ContentTask.spawn(browser, null, function() {
+    let shistory = docShell.QueryInterface(Ci.nsIInterfaceRequestor)
+                           .getInterface(Ci.nsISHistory);
+    return shistory.index;
   });
 }
 
-function runTests() {
-  duplicate(0, "maintained the original index", function() {
-    gBrowser.removeCurrentTab();
-
-    duplicate(-1, "went back", function() {
-      duplicate(1, "went forward", function() {
-        gBrowser.removeCurrentTab();
-        gBrowser.removeCurrentTab();
-        gBrowser.addTab();
-        gBrowser.removeCurrentTab();
-        finish();
-      });
-    });
-  });
-}
-
-function duplicate(delta, msg, cb) {
-  var start = gBrowser.sessionHistory.index;
+let duplicate = Task.async(function* (delta, msg, cb) {
+  var startIndex = yield promiseGetIndex(gBrowser.selectedBrowser);
 
   duplicateTabIn(gBrowser.selectedTab, "tab", delta);
+
   let tab = gBrowser.selectedTab;
-
-  tab.addEventListener("SSTabRestored", function() {
-    is(gBrowser.sessionHistory.index, start + delta, msg);
-    executeSoon(cb);
-  }, {once: true});
-}
+  yield BrowserTestUtils.waitForEvent(tab, "SSTabRestored");
 
-function loadAndWait(url, cb) {
-  gBrowser.selectedBrowser.addEventListener("load", function() {
-    executeSoon(cb);
-  }, {capture: true, once: true});
-
-  gBrowser.loadURI(url);
-}
+  let endIndex = yield promiseGetIndex(gBrowser.selectedBrowser);
+  is(endIndex, startIndex + delta, msg);
+});