--- a/.clang-format-ignore
+++ b/.clang-format-ignore
@@ -55,17 +55,16 @@
 ^media/libvpx/.*
 ^media/libyuv/.*
 ^media/mtransport/third_party/.*
 ^media/openmax_dl/.*
 ^media/pocketsphinx/.*
 ^media/sphinxbase/.*
 ^media/webrtc/trunk/.*
 ^media/webrtc/signaling/src/sdp/sipcc/.*
-^memory/jemalloc/src/.*
 ^mfbt/decimal/.*
 ^mfbt/double-conversion/source/.*
 ^mfbt/lz4.*
 ^mobile/android/thirdparty/.*
 ^modules/brotli/.*
 ^modules/fdlibm/.*
 ^modules/freetype2/.*
 ^modules/libbz2/.*

--- a/.cron.yml
+++ b/.cron.yml
@@ -51,17 +51,17 @@ jobs:
           - mozilla-central
           - mozilla-aurora
           - date
       when:
         by-project:
             # Match buildbot starts for now
             date: [{hour: 15, minute: 0}]
             mozilla-central: [{hour: 10, minute: 0}]
-            mozilla-aurora: [{hour: 7, minute: 45}]  # Buildbot uses minute 40
+            mozilla-aurora: [] # bug 1358976
             # No default
 
     - name: nightly-mochitest-valgrind
       job:
           type: decision-task
           treeherder-symbol: Vg
           target-tasks-method: mochitest_valgrind
       run-on-projects:

--- a/.eslintignore
+++ b/.eslintignore
@@ -73,20 +73,17 @@ browser/extensions/pdfjs/content/web**
 browser/extensions/pocket/content/panels/js/tmpl.js
 browser/extensions/pocket/content/panels/js/vendor/**
 browser/locales/**
 # generated or library files in activity-stream
 browser/extensions/activity-stream/data/content/activity-stream.bundle.js
 browser/extensions/activity-stream/vendor/**
 # imported from chromium
 browser/extensions/mortar/**
-
-# caps/ exclusions
-caps/tests/mochitest/browser_checkloaduri.js
-
+
 # devtools/ exclusions
 devtools/client/canvasdebugger/**
 devtools/client/commandline/**
 devtools/client/debugger/**
 devtools/client/framework/**
 !devtools/client/framework/devtools.js
 !devtools/client/framework/devtools-browser.js
 !devtools/client/framework/selection.js

--- a/accessible/generic/DocAccessible.cpp
+++ b/accessible/generic/DocAccessible.cpp
@@ -1977,19 +1977,29 @@ DocAccessible::ContentRemoved(Accessible
   Accessible* parent = aChild->Parent();
   MOZ_DIAGNOSTIC_ASSERT(parent, "Unattached accessible from tree");
 
 #ifdef A11Y_LOG
   logging::TreeInfo("process content removal", 0,
                     "container", parent, "child", aChild, nullptr);
 #endif
 
+  // XXX: event coalescence may kill us
+  RefPtr<Accessible> kungFuDeathGripChild(aChild);
+
   TreeMutation mt(parent);
   mt.BeforeRemoval(aChild);
-  MOZ_DIAGNOSTIC_ASSERT(aChild->Parent(), "Unparented #1");
+
+  if (aChild->IsDefunct()) {
+    MOZ_ASSERT_UNREACHABLE("Event coalescence killed the accessible");
+    mt.Done();
+    return;
+  }
+
+  MOZ_DIAGNOSTIC_ASSERT(aChild->Parent(), "Alive but unparented #1");
 
   if (aChild->IsRelocated()) {
     nsTArray<RefPtr<Accessible> >* owned = mARIAOwnsHash.Get(parent);
     MOZ_ASSERT(owned, "IsRelocated flag is out of sync with mARIAOwnsHash");
     owned->RemoveElement(aChild);
     if (owned->Length() == 0) {
       mARIAOwnsHash.Remove(parent);
     }

--- a/aclocal.m4
+++ b/aclocal.m4
@@ -22,17 +22,16 @@ builtin(include, build/autoconf/compiler
 builtin(include, build/autoconf/expandlibs.m4)dnl
 builtin(include, build/autoconf/arch.m4)dnl
 builtin(include, build/autoconf/android.m4)dnl
 builtin(include, build/autoconf/zlib.m4)dnl
 builtin(include, build/autoconf/icu.m4)dnl
 builtin(include, build/autoconf/clang-plugin.m4)dnl
 builtin(include, build/autoconf/alloc.m4)dnl
 builtin(include, build/autoconf/ios.m4)dnl
-builtin(include, build/autoconf/jemalloc.m4)dnl
 builtin(include, build/autoconf/sanitize.m4)dnl
 
 MOZ_PROG_CHECKMSYS()
 
 # Read the user's .mozconfig script.  We can't do this in
 # configure.in: autoconf puts the argument parsing code above anything
 # expanded from configure.in, and we need to get the configure options
 # from .mozconfig in place before that argument parsing code.

--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -1646,8 +1646,10 @@ pref("extensions.formautofill.loglevel",
 // Whether or not to restore a session with lazy-browser tabs.
 pref("browser.sessionstore.restore_tabs_lazily", true);
 
 // Enable safebrowsing v4 tables (suffixed by "-proto") update.
 #ifdef NIGHTLY_BUILD
 pref("urlclassifier.malwareTable", "goog-malware-shavar,goog-unwanted-shavar,goog-malware-proto,goog-unwanted-proto,test-malware-simple,test-unwanted-simple");
 pref("urlclassifier.phishTable", "goog-phish-shavar,goog-phish-proto,test-phish-simple");
 #endif
+
+pref("browser.suppress_first_window_animation", true);

--- a/browser/base/content/abouthome/aboutHome.css
+++ b/browser/base/content/abouthome/aboutHome.css
@@ -109,30 +109,28 @@ a {
 #searchSubmit {
   margin-inline-start: -1px;
   color: transparent;
   background: url("chrome://browser/skin/search-arrow-go.svg") center center no-repeat, linear-gradient(hsla(0,0%,100%,.8), hsla(0,0%,100%,.1)) padding-box;
   -moz-context-properties: fill;
   fill: #616366;
   padding: 0;
   border: 1px solid;
-  border-color: hsla(210,54%,20%,.15) hsla(210,54%,20%,.17) hsla(210,54%,20%,.2);
+  border-color: hsla(210,54%,20%,.15) hsla(210,54%,20%,.17) hsla(210,54%,20%,.2) transparent;
   border-radius: 0 2px 2px 0;
-  border-inline-start: 1px solid transparent;
   box-shadow: 0 0 2px hsla(0,0%,100%,.5) inset,
               0 1px 0 hsla(0,0%,100%,.2);
   cursor: pointer;
   transition-property: background-color, border-color, box-shadow;
   transition-duration: 150ms;
   width: 50px;
 }
 
 #searchSubmit:dir(rtl) {
-  border-radius: 2px 0 0 2px;
-  background-image: url("chrome://browser/skin/search-arrow-go-rtl.svg"), linear-gradient(hsla(0,0%,100%,.8), hsla(0,0%,100%,.1));
+  transform: scaleX(-1);
 }
 
 #searchText:focus + #searchSubmit,
 #searchText[keepfocus] + #searchSubmit,
 #searchText + #searchSubmit:hover,
 #searchText[autofocus] + #searchSubmit {
   border-color: #59b5fc #45a3e7 #3294d5;
 }
@@ -142,37 +140,25 @@ a {
 #searchText[autofocus] + #searchSubmit {
   background-image: url("chrome://browser/skin/search-arrow-go.svg"), linear-gradient(#4cb1ff, #1793e5);
   fill: white;
   box-shadow: 0 1px 0 hsla(0,0%,100%,.2) inset,
               0 0 0 1px hsla(0,0%,100%,.1) inset,
               0 1px 0 hsla(210,54%,20%,.03);
 }
 
-#searchText:focus + #searchSubmit:dir(rtl),
-#searchText[keepfocus] + #searchSubmit:dir(rtl),
-#searchText[autofocus] + #searchSubmit:dir(rtl) {
-  background-image: url("chrome://browser/skin/search-arrow-go-rtl.svg"), linear-gradient(#4cb1ff, #1793e5);
-  fill: white;
-}
-
 #searchText + #searchSubmit:hover {
   background-image: url("chrome://browser/skin/search-arrow-go.svg"), linear-gradient(#66bdff, #0d9eff);
   fill: white;
   box-shadow: 0 1px 0 hsla(0,0%,100%,.2) inset,
               0 0 0 1px hsla(0,0%,100%,.1) inset,
               0 1px 0 hsla(210,54%,20%,.03),
               0 0 4px hsla(206,100%,20%,.2);
 }
 
-#searchText + #searchSubmit:dir(rtl):hover {
-  background-image: url("chrome://browser/skin/search-arrow-go-rtl.svg"), linear-gradient(#66bdff, #0d9eff);
-  fill: white;
-}
-
 #searchText + #searchSubmit:hover:active {
   box-shadow: 0 1px 1px hsla(211,79%,6%,.1) inset,
               0 0 1px hsla(211,79%,6%,.2) inset;
   transition-duration: 0ms;
 }
 
 #defaultSnippet1,
 #defaultSnippet2,

--- a/browser/base/content/baseMenuOverlay.xul
+++ b/browser/base/content/baseMenuOverlay.xul
@@ -17,17 +17,17 @@
 <script type="application/javascript" src="chrome://browser/content/utilityOverlay.js"/>
 
 #ifdef XP_MACOSX
 <!-- nsMenuBarX hides these and uses them to build the Application menu.
      When using Carbon widgets for Mac OS X widgets, some of these are not
      used as they only apply to Cocoa widget builds. All version of Firefox
      through Firefox 2 will use Carbon widgets. -->
     <menupopup id="menu_ToolsPopup">
-        <menuitem id="menu_preferences" label="&preferencesCmdMac.label;" key="key_preferencesCmdMac" oncommand="openPreferences();"/>
+        <menuitem id="menu_preferences" label="&preferencesCmdMac.label;" key="key_preferencesCmdMac" oncommand="openPreferences(undefined, {origin: 'commandLineLegacy'});"/>
         <menuitem id="menu_mac_services" label="&servicesMenuMac.label;"/>
         <menuitem id="menu_mac_hide_app" label="&hideThisAppCmdMac2.label;" key="key_hideThisAppCmdMac"/>
         <menuitem id="menu_mac_hide_others" label="&hideOtherAppsCmdMac.label;" key="key_hideOtherAppsCmdMac"/>
         <menuitem id="menu_mac_show_all" label="&showAllAppsCmdMac.label;"/>
     </menupopup>
 <!-- Mac window menu -->
 #include ../../../toolkit/content/macWindowMenu.inc
 #endif

--- a/browser/base/content/browser-data-submission-info-bar.js
+++ b/browser/base/content/browser-data-submission-info-bar.js
@@ -64,19 +64,19 @@ var gDataNotificationInfoBar = {
       label: gNavigatorBundle.getString("dataReportingNotification.button.label"),
       accessKey: gNavigatorBundle.getString("dataReportingNotification.button.accessKey"),
       popup: null,
       callback: () => {
         this._actionTaken = true;
         // The advanced subpanes are only supported in the old organization, which will
         // be removed by bug 1349689.
         if (Preferences.get("browser.preferences.useOldOrganization", false)) {
-          window.openAdvancedPreferences("dataChoicesTab");
+          window.openAdvancedPreferences("dataChoicesTab", {origin: "dataReporting"});
         } else {
-          window.openPreferences("privacy-reports");
+          window.openPreferences("privacy-reports", {origin: "dataReporting"});
         }
       },
     }];
 
     this._log.info("Creating data reporting policy notification.");
     this._notificationBox.appendNotification(
       message,
       this._DATA_REPORTING_NOTIFICATION,

--- a/browser/base/content/browser-media.js
+++ b/browser/base/content/browser-media.js
@@ -162,17 +162,17 @@ var gEMEHandler = {
       Services.prefs.setBoolPref(firstPlayPref, true);
     } else {
       document.getElementById(anchorId).removeAttribute("firstplay");
     }
 
     let mainAction = {
       label: gNavigatorBundle.getString(btnLabelId),
       accessKey: gNavigatorBundle.getString(btnAccessKeyId),
-      callback() { openPreferences("panePrivacy"); },
+      callback() { openPreferences("panePrivacy", {origin: "browserMedia"}); },
       dismiss: true
     };
     let options = {
       dismissed: true,
       eventCallback: aTopic => aTopic == "swapping",
       learnMoreURL: Services.urlFormatter.formatURLPref("app.support.baseURL") + "drm-content",
     };
     PopupNotifications.show(browser, "drmContentPlaying", message, anchorId, mainAction, null, options);

--- a/browser/base/content/browser-menubar.inc
+++ b/browser/base/content/browser-menubar.inc
@@ -180,17 +180,17 @@
                           accesskey="&bidiSwitchTextDirectionItem.accesskey;"
                           hidden="true"/>
 #ifdef XP_UNIX
 #ifndef XP_MACOSX
                 <menuseparator/>
                 <menuitem id="menu_preferences"
                           label="&preferencesCmdUnix.label;"
                           accesskey="&preferencesCmdUnix.accesskey;"
-                          oncommand="openPreferences();"/>
+                          oncommand="openPreferences(undefined, {origin: 'menubar'});"/>
 #endif
 #endif
               </menupopup>
             </menu>
 
             <menu id="view-menu" label="&viewMenu.label;"
                   accesskey="&viewMenu.accesskey;">
               <menupopup id="menu_viewPopup"
@@ -527,17 +527,17 @@
                 <menupopup id="menu_mirrorTab-popup"
                            onpopupshowing="populateMirrorTabMenu(this)"/>
               </menu>
 #ifndef XP_UNIX
               <menuseparator id="prefSep"/>
               <menuitem id="menu_preferences"
                         label="&preferencesCmd2.label;"
                         accesskey="&preferencesCmd2.accesskey;"
-                        oncommand="openPreferences();"/>
+                        oncommand="openPreferences(undefined, {origin: 'menubar'});"/>
 #endif
               </menupopup>
             </menu>
 
 #ifdef XP_MACOSX
           <menu id="windowMenu" />
 #endif
           <menu id="helpMenu" />

--- a/browser/base/content/browser-sets.inc
+++ b/browser/base/content/browser-sets.inc
@@ -88,17 +88,17 @@
     <command id="cmd_fullZoomReset"   oncommand="FullZoom.reset()"/>
     <command id="cmd_fullZoomToggle"  oncommand="ZoomManager.toggleZoom();"/>
     <command id="cmd_gestureRotateLeft" oncommand="gGestureSupport.rotate(event.sourceEvent)"/>
     <command id="cmd_gestureRotateRight" oncommand="gGestureSupport.rotate(event.sourceEvent)"/>
     <command id="cmd_gestureRotateEnd" oncommand="gGestureSupport.rotateEnd()"/>
     <command id="Browser:OpenLocation" oncommand="openLocation();"/>
     <command id="Browser:RestoreLastSession" oncommand="restoreLastSession();" disabled="true"/>
     <command id="Browser:NewUserContextTab" oncommand="openNewUserContextTab(event.sourceEvent);"/>
-    <command id="Browser:OpenAboutContainers" oncommand="openPreferences('paneContainers');"/>
+    <command id="Browser:OpenAboutContainers" oncommand="openPreferences('paneContainers', {origin: 'ContainersCommand'});"/>
 
     <command id="Tools:Search" oncommand="BrowserSearch.webSearch();"/>
     <command id="Tools:Downloads" oncommand="BrowserDownloadsUI();"/>
     <command id="Tools:Addons" oncommand="BrowserOpenAddonsMgr();"/>
     <command id="Tools:Sanitize"
      oncommand="Cc['@mozilla.org/browser/browserglue;1'].getService(Ci.nsIBrowserGlue).sanitize(window);"/>
     <command id="Tools:PrivateBrowsing"
       oncommand="OpenBrowserWindow({private: true});"/>

--- a/browser/base/content/browser-sync.js
+++ b/browser/base/content/browser-sync.js
@@ -236,27 +236,27 @@ var gSync = {
     if (state.syncing != syncingUI) { // Do we need to update the UI?
       state.syncing ? this.onActivityStart() : this.onActivityStop();
     }
   },
 
   onMenuPanelCommand() {
     switch (this.panelUIFooter.getAttribute("fxastatus")) {
     case "signedin":
-      this.openPrefs("menupanel");
+      this.openPrefs("menupanel", "fxaSignedin");
       break;
     case "error":
       if (this.panelUIFooter.getAttribute("fxastatus") == "unverified") {
-        this.openPrefs("menupanel");
+        this.openPrefs("menupanel", "fxaError");
       } else {
         this.openSignInAgainPage("menupanel");
       }
       break;
     default:
-      this.openPrefs("menupanel");
+      this.openPrefs("menupanel", "fxa");
       break;
     }
 
     PanelUI.hide();
   },
 
   openAccountsPage(action, urlParams = {}) {
     let params = new URLSearchParams();
@@ -434,18 +434,18 @@ var gSync = {
     }
     const state = UIState.get();
     if (state.status == UIState.STATUS_SIGNED_IN) {
       setTimeout(() => Weave.Service.errorHandler.syncAndReportErrors(), 0);
     }
     Services.obs.notifyObservers(null, "cloudsync:user-sync");
   },
 
-  openPrefs(entryPoint = "syncbutton") {
-    window.openPreferences("paneSync", { urlParams: { entrypoint: entryPoint } });
+  openPrefs(entryPoint = "syncbutton", origin = undefined) {
+    window.openPreferences("paneSync", { origin, urlParams: { entrypoint: entryPoint } });
   },
 
   openSyncedTabsPanel() {
     let placement = CustomizableUI.getPlacementOfWidget("sync-button");
     let area = placement ? placement.area : CustomizableUI.AREA_NAVBAR;
     let anchor = document.getElementById("sync-button") ||
                  document.getElementById("PanelUI-menu-button");
     if (area == CustomizableUI.AREA_PANEL) {

--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -522,19 +522,19 @@ const gStoragePressureObserver = {
       buttons.push({
         label: prefStrBundle.getString(prefButtonLabelStringID),
         accessKey: prefStrBundle.getString(prefButtonAccesskeyStringID),
         callback(notificationBar, button) {
           // The advanced subpanes are only supported in the old organization, which will
           // be removed by bug 1349689.
           let win = gBrowser.ownerGlobal;
           if (Preferences.get("browser.preferences.useOldOrganization", false)) {
-            win.openAdvancedPreferences("networkTab");
+            win.openAdvancedPreferences("networkTab", {origin: "storagePressure"});
           } else {
-            win.openPreferences("panePrivacy");
+            win.openPreferences("panePrivacy", {origin: "storagePressure"});
           }
         }
       });
     }
 
     notificationBox.appendNotification(
       msg, "storage-pressure-notification", null, notificationBox.PRIORITY_WARNING_HIGH, buttons, null);
   }
@@ -6358,19 +6358,19 @@ var OfflineApps = {
       });
     }
   },
 
   manage() {
     // The advanced subpanes are only supported in the old organization, which will
     // be removed by bug 1349689.
     if (Preferences.get("browser.preferences.useOldOrganization", false)) {
-      openAdvancedPreferences("networkTab");
+      openAdvancedPreferences("networkTab", {origin: "offlineApps"});
     } else {
-      openPreferences("panePrivacy");
+      openPreferences("panePrivacy", {origin: "offlineApps"});
     }
   },
 
   receiveMessage(msg) {
     switch (msg.name) {
       case "OfflineApps:CheckUsage":
         let uri = makeURI(msg.data.uri);
         if (this._usedMoreThanWarnQuota(uri)) {

--- a/browser/base/content/newtab/newTab.css
+++ b/browser/base/content/newtab/newTab.css
@@ -302,30 +302,28 @@ body.compact #newtab-search-container {
 #newtab-search-submit {
   margin-inline-start: -1px;
   color: transparent;
   background: url("chrome://browser/skin/search-arrow-go.svg") center center no-repeat, linear-gradient(hsla(0,0%,100%,.8), hsla(0,0%,100%,.1)) padding-box;
   -moz-context-properties: fill;
   fill: #616366;
   padding: 0;
   border: 1px solid;
-  border-color: hsla(210,54%,20%,.15) hsla(210,54%,20%,.17) hsla(210,54%,20%,.2);
+  border-color: hsla(210,54%,20%,.15) hsla(210,54%,20%,.17) hsla(210,54%,20%,.2) transparent;
   border-radius: 0 2px 2px 0;
-  border-inline-start: 1px solid transparent;
   box-shadow: 0 0 2px hsla(0,0%,100%,.5) inset,
               0 1px 0 hsla(0,0%,100%,.2);
   cursor: pointer;
   transition-property: background-color, border-color, box-shadow;
   transition-duration: 150ms;
   width: 50px;
 }
 
 #newtab-search-submit:dir(rtl) {
-  border-radius: 2px 0 0 2px;
-  background-image: url("chrome://browser/skin/search-arrow-go-rtl.svg"), linear-gradient(hsla(0,0%,100%,.8), hsla(0,0%,100%,.1));
+  transform: scaleX(-1);
 }
 
 #newtab-search-text:focus + #newtab-search-submit,
 #newtab-search-text + #newtab-search-submit:hover,
 #newtab-search-text[autofocus] + #newtab-search-submit {
   border-color: #59b5fc #45a3e7 #3294d5;
 }
 
@@ -349,24 +347,16 @@ body.compact #newtab-search-container {
 }
 
 #newtab-search-text + #newtab-search-submit:hover:active {
   box-shadow: 0 1px 1px hsla(211,79%,6%,.1) inset,
               0 0 1px hsla(211,79%,6%,.2) inset;
   transition-duration: 0ms;
 }
 
-#newtab-search-text:focus + #newtab-search-submit:dir(rtl),
-#newtab-search-text[keepfocus] + #newtab-search-submit:dir(rtl),
-#newtab-search-text[autofocus] + #newtab-search-submit:dir(rtl),
-#newtab-search-text + #newtab-search-submit:dir(rtl):hover {
-  background-image: url("chrome://browser/skin/search-arrow-go-rtl.svg"), linear-gradient(#4cb1ff, #1793e5);
-  fill: white;
-}
-
 /* CUSTOMIZE */
 #newtab-customize-overlay {
   opacity: 0;
   display: none;
   width: 100%;
   height: 100%;
   background: #F9F9F9;
   z-index: 100;

--- a/browser/base/content/test/alerts/browser_notification_do_not_disturb.js
+++ b/browser/base/content/test/alerts/browser_notification_do_not_disturb.js
@@ -30,17 +30,17 @@ function test() {
   });
 
   pm.add(makeURI(notificationURL), "desktop-notification", pm.ALLOW_ACTION);
 
   // Make sure that do-not-disturb is not enabled.
   ok(!ALERT_SERVICE.manualDoNotDisturb, "Alert service should not be disabled when test starts");
   ALERT_SERVICE.manualDoNotDisturb = false;
 
-  tab = gBrowser.addTab(notificationURL);
+  tab = BrowserTestUtils.addTab(gBrowser, notificationURL);
   gBrowser.selectedTab = tab;
   tab.linkedBrowser.addEventListener("load", onLoad, true);
 }
 
 function onLoad() {
   tab.linkedBrowser.removeEventListener("load", onLoad, true);
   openNotification(tab.linkedBrowser, "showNotification2").then(onAlertShowing);
 }

--- a/browser/base/content/test/alerts/browser_notification_remove_permission.js
+++ b/browser/base/content/test/alerts/browser_notification_remove_permission.js
@@ -12,17 +12,17 @@ function test() {
   registerCleanupFunction(function() {
     pm.remove(makeURI(notificationURL), "desktop-notification");
     gBrowser.removeTab(tab);
     window.restore();
   });
 
   pm.add(makeURI(notificationURL), "desktop-notification", pm.ALLOW_ACTION);
 
-  tab = gBrowser.addTab(notificationURL);
+  tab = BrowserTestUtils.addTab(gBrowser, notificationURL);
   gBrowser.selectedTab = tab;
   tab.linkedBrowser.addEventListener("load", onLoad, true);
 }
 
 function onLoad() {
   tab.linkedBrowser.removeEventListener("load", onLoad, true);
   openNotification(tab.linkedBrowser, "showNotification2").then(onAlertShowing);
 }

--- a/browser/base/content/test/captivePortal/browser_captivePortal_certErrorUI.js
+++ b/browser/base/content/test/captivePortal/browser_captivePortal_certErrorUI.js
@@ -20,17 +20,17 @@ add_task(async function checkCaptivePort
 
   info("Waiting for captive portal state to be propagated to the content process.");
   await captivePortalStatePropagated;
 
   // Open a page with a cert error.
   let browser;
   let certErrorLoaded;
   let errorTab = await BrowserTestUtils.openNewForegroundTab(gBrowser, () => {
-    let tab = gBrowser.addTab(BAD_CERT_PAGE);
+    let tab = BrowserTestUtils.addTab(gBrowser, BAD_CERT_PAGE);
     gBrowser.selectedTab = tab;
     browser = gBrowser.selectedBrowser;
     certErrorLoaded = BrowserTestUtils.waitForContentEvent(browser, "DOMContentLoaded");
     return tab;
   }, false);
 
   info("Waiting for cert error page to load.")
   await certErrorLoaded;

--- a/browser/base/content/test/general/browser_aboutCertError.js
+++ b/browser/base/content/test/general/browser_aboutCertError.js
@@ -12,17 +12,17 @@ const BAD_STS_CERT = "https://badchain.i
 const {TabStateFlusher} = Cu.import("resource:///modules/sessionstore/TabStateFlusher.jsm", {});
 const ss = Cc["@mozilla.org/browser/sessionstore;1"].getService(Ci.nsISessionStore);
 
 add_task(async function checkReturnToAboutHome() {
   info("Loading a bad cert page directly and making sure 'return to previous page' goes to about:home");
   let browser;
   let certErrorLoaded;
   let tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, () => {
-    gBrowser.selectedTab = gBrowser.addTab(BAD_CERT);
+    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, BAD_CERT);
     browser = gBrowser.selectedBrowser;
     certErrorLoaded = BrowserTestUtils.waitForErrorPage(browser);
   }, false);
 
   info("Loading and waiting for the cert error");
   await certErrorLoaded;
 
   is(browser.webNavigation.canGoBack, false, "!webNavigation.canGoBack");
@@ -121,17 +121,17 @@ add_task(async function checkAppBuildIDI
 
 const PREF_BLOCKLIST_CLOCK_SKEW_SECONDS = "services.blocklist.clock_skew_seconds";
 
 add_task(async function checkWrongSystemTimeWarning() {
   async function setUpPage() {
     let browser;
     let certErrorLoaded;
     await BrowserTestUtils.openNewForegroundTab(gBrowser, () => {
-      gBrowser.selectedTab = gBrowser.addTab(BAD_CERT);
+      gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, BAD_CERT);
       browser = gBrowser.selectedBrowser;
       certErrorLoaded = BrowserTestUtils.waitForErrorPage(browser);
     }, false);
 
     info("Loading and waiting for the cert error");
     await certErrorLoaded;
 
     return await ContentTask.spawn(browser, null, async function() {
@@ -219,17 +219,17 @@ add_task(async function checkWrongSystem
   await BrowserTestUtils.removeTab(gBrowser.selectedTab);
 });
 
 add_task(async function checkAdvancedDetails() {
   info("Loading a bad cert page and verifying the main error and advanced details section");
   let browser;
   let certErrorLoaded;
   await BrowserTestUtils.openNewForegroundTab(gBrowser, () => {
-    gBrowser.selectedTab = gBrowser.addTab(BAD_CERT);
+    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, BAD_CERT);
     browser = gBrowser.selectedBrowser;
     certErrorLoaded = BrowserTestUtils.waitForErrorPage(browser);
   }, false);
 
   info("Loading and waiting for the cert error");
   await certErrorLoaded;
 
   let message = await ContentTask.spawn(browser, null, async function() {
@@ -281,17 +281,17 @@ add_task(async function checkAdvancedDet
   await BrowserTestUtils.removeTab(gBrowser.selectedTab);
 });
 
 add_task(async function checkAdvancedDetailsForHSTS() {
   info("Loading a bad STS cert page and verifying the advanced details section");
   let browser;
   let certErrorLoaded;
   await BrowserTestUtils.openNewForegroundTab(gBrowser, () => {
-    gBrowser.selectedTab = gBrowser.addTab(BAD_STS_CERT);
+    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, BAD_STS_CERT);
     browser = gBrowser.selectedBrowser;
     certErrorLoaded = BrowserTestUtils.waitForErrorPage(browser);
   }, false);
 
   info("Loading and waiting for the cert error");
   await certErrorLoaded;
 
   let message = await ContentTask.spawn(browser, null, async function() {
@@ -350,17 +350,17 @@ add_task(async function checkAdvancedDet
   await BrowserTestUtils.removeTab(gBrowser.selectedTab);
 });
 
 add_task(async function checkUnknownIssuerLearnMoreLink() {
   info("Loading a cert error for self-signed pages and checking the correct link is shown");
   let browser;
   let certErrorLoaded;
   await BrowserTestUtils.openNewForegroundTab(gBrowser, () => {
-    gBrowser.selectedTab = gBrowser.addTab(UNKNOWN_ISSUER);
+    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, UNKNOWN_ISSUER);
     browser = gBrowser.selectedBrowser;
     certErrorLoaded = BrowserTestUtils.waitForErrorPage(browser);
   }, false);
 
   info("Loading and waiting for the cert error");
   await certErrorLoaded;
 
   let href = await ContentTask.spawn(browser, null, async function() {

--- a/browser/base/content/test/general/browser_aboutHealthReport.js
+++ b/browser/base/content/test/general/browser_aboutHealthReport.js
@@ -110,17 +110,17 @@ function test() {
     }
 
     finish();
   })();
 }
 
 function promiseNewTabLoadEvent(aUrl, aEventType = "load") {
   return new Promise(resolve => {
-    let tab = gBrowser.selectedTab = gBrowser.addTab(aUrl);
+    let tab = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, aUrl);
     tab.linkedBrowser.addEventListener(aEventType, function(event) {
       let iframe = tab.linkedBrowser.contentDocument.getElementById("remote-report");
         iframe.addEventListener("load", function frameLoad(e) {
           if (iframe.contentWindow.location.href == "about:blank" ||
               e.target != iframe) {
             return;
           }
           iframe.removeEventListener("load", frameLoad);

--- a/browser/base/content/test/general/browser_aboutNetError.js
+++ b/browser/base/content/test/general/browser_aboutNetError.js
@@ -11,17 +11,17 @@ const LOW_TLS_VERSION = "https://tls1.ex
 const {TabStateFlusher} = Cu.import("resource:///modules/sessionstore/TabStateFlusher.jsm", {});
 const ss = Cc["@mozilla.org/browser/sessionstore;1"].getService(Ci.nsISessionStore);
 
 add_task(async function checkReturnToPreviousPage() {
   info("Loading a TLS page that isn't supported, ensure we have a fix button and clicking it then loads the page");
   let browser;
   let pageLoaded;
   await BrowserTestUtils.openNewForegroundTab(gBrowser, () => {
-    gBrowser.selectedTab = gBrowser.addTab(LOW_TLS_VERSION);
+    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, LOW_TLS_VERSION);
     browser = gBrowser.selectedBrowser;
     pageLoaded = BrowserTestUtils.waitForErrorPage(browser);
   }, false);
 
   info("Loading and waiting for the net error");
   await pageLoaded;
 
   // NB: This code assumes that the error page and the test page load in the

--- a/browser/base/content/test/general/browser_alltabslistener.js
+++ b/browser/base/content/test/general/browser_alltabslistener.js
@@ -82,18 +82,18 @@ var gFrontNotifications, gAllNotificatio
 var gBackgroundTab, gForegroundTab, gBackgroundBrowser, gForegroundBrowser, gTestBrowser;
 var gTestPage = "/browser/browser/base/content/test/general/alltabslistener.html";
 const kBasePage = "http://example.org/browser/browser/base/content/test/general/dummy_page.html";
 var gNextTest;
 
 function test() {
   waitForExplicitFinish();
 
-  gBackgroundTab = gBrowser.addTab();
-  gForegroundTab = gBrowser.addTab();
+  gBackgroundTab = BrowserTestUtils.addTab(gBrowser);
+  gForegroundTab = BrowserTestUtils.addTab(gBrowser);
   gBackgroundBrowser = gBrowser.getBrowserForTab(gBackgroundTab);
   gForegroundBrowser = gBrowser.getBrowserForTab(gForegroundTab);
   gBrowser.selectedTab = gForegroundTab;
 
   // We must wait until a page has completed loading before
   // starting tests or we get notifications from that
   let promises = [
     waitForDocLoadComplete(gBackgroundBrowser),

--- a/browser/base/content/test/general/browser_bookmark_titles.js
+++ b/browser/base/content/test/general/browser_bookmark_titles.js
@@ -15,17 +15,17 @@ var tests = [
     ["data:application/vnd.mozilla.xul+xml,",
      "data:application/vnd.mozilla.xul+xml,"],
     // about:certerror
     ["https://untrusted.example.com/somepage.html",
      "https://untrusted.example.com/somepage.html"]
 ];
 
 add_task(async function() {
-    gBrowser.selectedTab = gBrowser.addTab();
+    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
     let browser = gBrowser.selectedBrowser;
     browser.stop(); // stop the about:blank load.
 
     // Test that a bookmark of each URI gets the corresponding default title.
     for (let i = 0; i < tests.length; ++i) {
         let [uri, title] = tests[i];
 
         let promiseLoaded = promisePageLoaded(browser);

--- a/browser/base/content/test/general/browser_bug1015721.js
+++ b/browser/base/content/test/general/browser_bug1015721.js
@@ -6,18 +6,18 @@
 const TEST_PAGE = "http://example.org/browser/browser/base/content/test/general/zoom_test.html";
 
 var gTab1, gTab2, gLevel1;
 
 function test() {
   waitForExplicitFinish();
 
   (async function() {
-    gTab1 = gBrowser.addTab();
-    gTab2 = gBrowser.addTab();
+    gTab1 = BrowserTestUtils.addTab(gBrowser);
+    gTab2 = BrowserTestUtils.addTab(gBrowser);
 
     await FullZoomHelper.selectTabAndWaitForLocationChange(gTab1);
     await FullZoomHelper.load(gTab1, TEST_PAGE);
     await FullZoomHelper.load(gTab2, TEST_PAGE);
   })().then(zoomTab1, FullZoomHelper.failAndContinue(finish));
 }
 
 function zoomTab1() {

--- a/browser/base/content/test/general/browser_bug380960.js
+++ b/browser/base/content/test/general/browser_bug380960.js
@@ -1,11 +1,11 @@
 function test() {
-  var tab = gBrowser.addTab("about:blank", { skipAnimation: true });
+  var tab = BrowserTestUtils.addTab(gBrowser, "about:blank", { skipAnimation: true });
   gBrowser.removeTab(tab);
   is(tab.parentNode, null, "tab removed immediately");
 
-  tab = gBrowser.addTab("about:blank", { skipAnimation: true });
+  tab = BrowserTestUtils.addTab(gBrowser, "about:blank", { skipAnimation: true });
   gBrowser.removeTab(tab, { animate: true });
   gBrowser.removeTab(tab);
   is(tab.parentNode, null, "tab removed immediately when calling removeTab again after the animation was kicked off");
 }
 

--- a/browser/base/content/test/general/browser_bug386835.js
+++ b/browser/base/content/test/general/browser_bug386835.js
@@ -4,19 +4,19 @@ var gTab1, gTab2, gTab3;
 var gLevel;
 const BACK = 0;
 const FORWARD = 1;
 
 function test() {
   waitForExplicitFinish();
 
   (async function() {
-    gTab1 = gBrowser.addTab(gTestPage);
-    gTab2 = gBrowser.addTab();
-    gTab3 = gBrowser.addTab();
+    gTab1 = BrowserTestUtils.addTab(gBrowser, gTestPage);
+    gTab2 = BrowserTestUtils.addTab(gBrowser);
+    gTab3 = BrowserTestUtils.addTab(gBrowser);
 
     await FullZoomHelper.selectTabAndWaitForLocationChange(gTab1);
     await FullZoomHelper.load(gTab1, gTestPage);
     await FullZoomHelper.load(gTab2, gTestPage);
   })().then(secondPageLoaded, FullZoomHelper.failAndContinue(finish));
 }
 
 function secondPageLoaded() {

--- a/browser/base/content/test/general/browser_bug406216.js
+++ b/browser/base/content/test/general/browser_bug406216.js
@@ -15,17 +15,17 @@ const URIS = ["about:config",
               "data:text/html,<title>OK</title>"];
 
 function test() {
   waitForExplicitFinish();
   URIS.forEach(addTab);
 }
 
 function addTab(aURI, aIndex) {
-  var tab = gBrowser.addTab(aURI);
+  var tab = BrowserTestUtils.addTab(gBrowser, aURI);
   if (aIndex == 0)
     gBrowser.removeTab(gBrowser.tabs[0], {skipPermitUnload: true});
 
   tab.linkedBrowser.addEventListener("load", function(event) {
     if (++count == URIS.length)
       executeSoon(doTabsTest);
   }, {capture: true, once: true});
 }
@@ -41,12 +41,12 @@ function doTabsTest() {
       if (aTab != closedTab && aTab.linkedBrowser.currentURI.scheme == scheme)
         gBrowser.removeTab(aTab, {skipPermitUnload: true});
     });
   }, {capture: true, once: true});
 
   gBrowser.removeTab(gBrowser.tabs[0], {skipPermitUnload: true});
   is(gBrowser.tabs.length, 1, "Related tabs are not closed unexpectedly");
 
-  gBrowser.addTab("about:blank");
+  BrowserTestUtils.addTab(gBrowser, "about:blank");
   gBrowser.removeTab(gBrowser.tabs[0], {skipPermitUnload: true});
   finish();
 }

--- a/browser/base/content/test/general/browser_bug416661.js
+++ b/browser/base/content/test/general/browser_bug416661.js
@@ -31,13 +31,13 @@ function end_test_prefNotSet() {
     finish();
   })();
 }
 
 function test() {
   waitForExplicitFinish();
 
   (async function() {
-    tabElm = gBrowser.addTab();
+    tabElm = BrowserTestUtils.addTab(gBrowser);
     await FullZoomHelper.selectTabAndWaitForLocationChange(tabElm);
     await FullZoomHelper.load(tabElm, "http://mochi.test:8888/browser/browser/base/content/test/general/zoom_test.html");
   })().then(start_test_prefNotSet, FullZoomHelper.failAndContinue(finish));
 }

--- a/browser/base/content/test/general/browser_bug419612.js
+++ b/browser/base/content/test/general/browser_bug419612.js
@@ -1,18 +1,18 @@
 function test() {
   waitForExplicitFinish();
 
   (async function() {
     let testPage = "http://example.org/browser/browser/base/content/test/general/dummy_page.html";
-    let tab1 = gBrowser.addTab();
+    let tab1 = BrowserTestUtils.addTab(gBrowser);
     await FullZoomHelper.selectTabAndWaitForLocationChange(tab1);
     await FullZoomHelper.load(tab1, testPage);
 
-    let tab2 = gBrowser.addTab();
+    let tab2 = BrowserTestUtils.addTab(gBrowser);
     await FullZoomHelper.load(tab2, testPage);
 
     FullZoom.enlarge();
     let tab1Zoom = ZoomManager.getZoomForBrowser(tab1.linkedBrowser);
 
     await FullZoomHelper.selectTabAndWaitForLocationChange(tab2);
     let tab2Zoom = ZoomManager.getZoomForBrowser(tab2.linkedBrowser);
     is(tab2Zoom, tab1Zoom, "Zoom should affect background tabs");

--- a/browser/base/content/test/general/browser_bug423833.js
+++ b/browser/base/content/test/general/browser_bug423833.js
@@ -10,17 +10,17 @@ var test2tab;
 var test3window;
 
 // We use setInterval instead of setTimeout to avoid race conditions on error doc loads
 var intervalID;
 
 function test() {
   waitForExplicitFinish();
 
-  gBrowser.selectedTab = gBrowser.addTab();
+  gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
   gBrowser.selectedBrowser.addEventListener("load", test1Setup, true);
   content.location = testPage;
 }
 
 function test1Setup() {
   if (content.frames.length < 2 ||
       content.frames[1].location != invalidPage)
     // The error frame hasn't loaded yet

--- a/browser/base/content/test/general/browser_bug431826.js
+++ b/browser/base/content/test/general/browser_bug431826.js
@@ -1,14 +1,14 @@
 function remote(task) {
   return ContentTask.spawn(gBrowser.selectedBrowser, null, task);
 }
 
 add_task(async function() {
-  gBrowser.selectedTab = gBrowser.addTab();
+  gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
 
   let promise = BrowserTestUtils.waitForErrorPage(gBrowser.selectedBrowser);
   gBrowser.loadURI("https://nocert.example.com/");
   await promise;
 
   await remote(() => {
     // Confirm that we are displaying the contributed error page, not the default
     let uri = content.document.documentURI;

--- a/browser/base/content/test/general/browser_bug432599.js
+++ b/browser/base/content/test/general/browser_bug432599.js
@@ -38,17 +38,17 @@ function add_bookmark(aURI, aTitle) {
                                               aURI, PlacesUtils.bookmarks.DEFAULT_INDEX,
                                               aTitle);
 }
 
 // test bug 432599
 function test() {
   waitForExplicitFinish();
 
-  gBrowser.selectedTab = gBrowser.addTab();
+  gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
   gBrowser.selectedBrowser.addEventListener("load", function() {
     waitForStarChange(false, initTest);
   }, {capture: true, once: true});
 
   content.location = testURL;
 }
 
 function initTest() {

--- a/browser/base/content/test/general/browser_bug435325.js
+++ b/browser/base/content/test/general/browser_bug435325.js
@@ -14,17 +14,17 @@ function test() {
   // Tests always connect to localhost, and per bug 87717, localhost is now
   // reachable in offline mode.  To avoid this, disable any proxy.
   proxyPrefValue = Services.prefs.getIntPref("network.proxy.type");
   Services.prefs.setIntPref("network.proxy.type", 0);
 
   Services.prefs.setBoolPref("browser.cache.disk.enable", false);
   Services.prefs.setBoolPref("browser.cache.memory.enable", false);
 
-  gBrowser.selectedTab = gBrowser.addTab("http://example.com/");
+  gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "http://example.com/");
 
   let contentScript = `
     let listener = function () {
       removeEventListener("DOMContentLoaded", listener);
       sendAsyncMessage("Test:DOMContentLoaded", { uri: content.document.documentURI });
     };
     addEventListener("DOMContentLoaded", listener);
   `;

--- a/browser/base/content/test/general/browser_bug441778.js
+++ b/browser/base/content/test/general/browser_bug441778.js
@@ -10,17 +10,17 @@
 function test() {
   waitForExplicitFinish();
 
   const TEST_PAGE_URL = 'data:text/html,<body><iframe src=""></iframe></body>';
   const TEST_IFRAME_URL = "http://test2.example.org/";
 
   (async function() {
     // Prepare the test tab
-    let tab = gBrowser.addTab();
+    let tab = BrowserTestUtils.addTab(gBrowser);
     await FullZoomHelper.selectTabAndWaitForLocationChange(tab);
 
     let testBrowser = tab.linkedBrowser;
 
     await FullZoomHelper.load(tab, TEST_PAGE_URL);
 
     // Change the zoom level and then save it so we can compare it to the level
     // after loading the sub-document.

--- a/browser/base/content/test/general/browser_bug462289.js
+++ b/browser/base/content/test/general/browser_bug462289.js
@@ -6,18 +6,18 @@ function focus_in_navbar() {
     parent = parent.parentNode;
 
   return parent != null;
 }
 
 function test() {
   waitForExplicitFinish();
 
-  tab1 = gBrowser.addTab("about:blank", {skipAnimation: true});
-  tab2 = gBrowser.addTab("about:blank", {skipAnimation: true});
+  tab1 = BrowserTestUtils.addTab(gBrowser, "about:blank", {skipAnimation: true});
+  tab2 = BrowserTestUtils.addTab(gBrowser, "about:blank", {skipAnimation: true});
 
   EventUtils.synthesizeMouseAtCenter(tab1, {});
   executeSoon(step2);
 }
 
 function step2() {
   is(gBrowser.selectedTab, tab1, "1st click on tab1 selects tab");
   isnot(document.activeElement, tab1, "1st click on tab1 does not activate tab");

--- a/browser/base/content/test/general/browser_bug477014.js
+++ b/browser/base/content/test/general/browser_bug477014.js
@@ -2,17 +2,17 @@
  * 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/. */
 
 // That's a gecko!
 const iconURLSpec = "data:image/png;base64,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";
 var testPage = "data:text/plain,test bug 477014";
 
 add_task(async function() {
-  let tabToDetach = gBrowser.addTab(testPage);
+  let tabToDetach = BrowserTestUtils.addTab(gBrowser, testPage);
   await waitForDocLoadComplete(tabToDetach.linkedBrowser);
 
   gBrowser.setIcon(tabToDetach, iconURLSpec,
                    Services.scriptSecurityManager.getSystemPrincipal());
   tabToDetach.setAttribute("busy", "true");
 
   // detach and set the listener on the new window
   let newWindow = gBrowser.replaceTabWithWindow(tabToDetach);

--- a/browser/base/content/test/general/browser_bug479408.js
+++ b/browser/base/content/test/general/browser_bug479408.js
@@ -1,11 +1,11 @@
 function test() {
   waitForExplicitFinish();
-  let tab = gBrowser.selectedTab = gBrowser.addTab(
+  let tab = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser,
     "http://mochi.test:8888/browser/browser/base/content/test/general/browser_bug479408_sample.html");
 
   gBrowser.addEventListener("DOMLinkAdded", function(aEvent) {
     executeSoon(function() {
       ok(!tab.linkedBrowser.engines,
          "the subframe's search engine wasn't detected");
 
       gBrowser.removeTab(tab);

--- a/browser/base/content/test/general/browser_bug491431.js
+++ b/browser/base/content/test/general/browser_bug491431.js
@@ -5,22 +5,22 @@
 var testPage = "data:text/plain,test bug 491431 Page";
 
 function test() {
   waitForExplicitFinish();
 
   let newWin, tabA, tabB;
 
   // test normal close
-  tabA = gBrowser.addTab(testPage);
+  tabA = BrowserTestUtils.addTab(gBrowser, testPage);
   gBrowser.tabContainer.addEventListener("TabClose", function(firstTabCloseEvent) {
     ok(!firstTabCloseEvent.detail.adoptedBy, "This was a normal tab close");
 
     // test tab close by moving
-    tabB = gBrowser.addTab(testPage);
+    tabB = BrowserTestUtils.addTab(gBrowser, testPage);
     gBrowser.tabContainer.addEventListener("TabClose", function(secondTabCloseEvent) {
       executeSoon(function() {
         ok(secondTabCloseEvent.detail.adoptedBy, "This was a tab closed by moving");
 
         // cleanup
         newWin.close();
         executeSoon(finish);
       });

--- a/browser/base/content/test/general/browser_bug495058.js
+++ b/browser/base/content/test/general/browser_bug495058.js
@@ -6,17 +6,17 @@
 const URIS = [
   "about:blank",
   "about:sessionrestore",
   "about:privatebrowsing",
 ];
 
 add_task(async function() {
   for (let uri of URIS) {
-    let tab = gBrowser.addTab();
+    let tab = BrowserTestUtils.addTab(gBrowser);
     await BrowserTestUtils.loadURI(tab.linkedBrowser, uri);
 
     let win = gBrowser.replaceTabWithWindow(tab);
     await TestUtils.topicObserved("browser-delayed-startup-finished",
                                   subject => subject == win);
     tab = win.gBrowser.selectedTab;
 
     // BrowserTestUtils doesn't get the add-on shims, which means that

--- a/browser/base/content/test/general/browser_bug521216.js
+++ b/browser/base/content/test/general/browser_bug521216.js
@@ -3,17 +3,17 @@ var actual = [];
 var tabIndex = -1;
 this.__defineGetter__("tab", () => gBrowser.tabs[tabIndex]);
 
 function test() {
   waitForExplicitFinish();
   tabIndex = gBrowser.tabs.length;
   gBrowser.addTabsProgressListener(progressListener);
   gBrowser.tabContainer.addEventListener("TabOpen", TabOpen);
-  gBrowser.addTab("data:text/html,<html><head><link href='about:logo' rel='shortcut icon'>");
+  BrowserTestUtils.addTab(gBrowser, "data:text/html,<html><head><link href='about:logo' rel='shortcut icon'>");
 }
 
 function record(aName) {
   info("got " + aName);
   if (actual.indexOf(aName) == -1)
     actual.push(aName);
   if (actual.length == expected.length) {
     is(actual.toString(), expected.toString(),

--- a/browser/base/content/test/general/browser_bug533232.js
+++ b/browser/base/content/test/general/browser_bug533232.js
@@ -1,30 +1,30 @@
 function test() {
   var tab1 = gBrowser.selectedTab;
-  var tab2 = gBrowser.addTab();
+  var tab2 = BrowserTestUtils.addTab(gBrowser);
   var childTab1;
   var childTab2;
 
-  childTab1 = gBrowser.addTab("about:blank", { relatedToCurrent: true });
+  childTab1 = BrowserTestUtils.addTab(gBrowser, "about:blank", { relatedToCurrent: true });
   gBrowser.selectedTab = childTab1;
   gBrowser.removeTab(gBrowser.selectedTab, { skipPermitUnload: true });
   is(idx(gBrowser.selectedTab), idx(tab1),
      "closing a tab next to its parent selects the parent");
 
-  childTab1 = gBrowser.addTab("about:blank", { relatedToCurrent: true });
+  childTab1 = BrowserTestUtils.addTab(gBrowser, "about:blank", { relatedToCurrent: true });
   gBrowser.selectedTab = tab2;
   gBrowser.selectedTab = childTab1;
   gBrowser.removeTab(gBrowser.selectedTab, { skipPermitUnload: true });
   is(idx(gBrowser.selectedTab), idx(tab2),
      "closing a tab next to its parent doesn't select the parent if another tab had been selected ad interim");
 
   gBrowser.selectedTab = tab1;
-  childTab1 = gBrowser.addTab("about:blank", { relatedToCurrent: true });
-  childTab2 = gBrowser.addTab("about:blank", { relatedToCurrent: true });
+  childTab1 = BrowserTestUtils.addTab(gBrowser, "about:blank", { relatedToCurrent: true });
+  childTab2 = BrowserTestUtils.addTab(gBrowser, "about:blank", { relatedToCurrent: true });
   gBrowser.selectedTab = childTab1;
   gBrowser.removeTab(gBrowser.selectedTab, { skipPermitUnload: true });
   is(idx(gBrowser.selectedTab), idx(childTab2),
      "closing a tab next to its parent selects the next tab with the same parent");
   gBrowser.removeTab(gBrowser.selectedTab, { skipPermitUnload: true });
   is(idx(gBrowser.selectedTab), idx(tab2),
      "closing the last tab in a set of child tabs doesn't go back to the parent");
 

--- a/browser/base/content/test/general/browser_bug537013.js
+++ b/browser/base/content/test/general/browser_bug537013.js
@@ -10,18 +10,18 @@ var texts = [
   "Klein bottle for sale. Inquire within.",
   "To err is human; to forgive is not company policy."
 ];
 
 var Clipboard = Cc["@mozilla.org/widget/clipboard;1"].getService(Ci.nsIClipboard);
 var HasFindClipboard = Clipboard.supportsFindClipboard();
 
 function addTabWithText(aText, aCallback) {
-  let newTab = gBrowser.addTab("data:text/html;charset=utf-8,<h1 id='h1'>" +
-                               aText + "</h1>");
+  let newTab = BrowserTestUtils.addTab(gBrowser, "data:text/html;charset=utf-8,<h1 id='h1'>" +
+                                       aText + "</h1>");
   tabs.push(newTab);
   gBrowser.selectedTab = newTab;
 }
 
 function setFindString(aString) {
   gFindBar.open();
   gFindBar._findField.focus();
   gFindBar._findField.select();

--- a/browser/base/content/test/general/browser_bug553455.js
+++ b/browser/base/content/test/general/browser_bug553455.js
@@ -432,17 +432,17 @@ function test_restartless() {
     let pm = Services.perms;
     pm.add(makeURI("http://example.com/"), "install", pm.ALLOW_ACTION);
 
     let progressPromise = waitForProgressNotification();
     let dialogPromise = waitForInstallDialog();
     let triggers = encodeURIComponent(JSON.stringify({
       "XPI": "restartless.xpi"
     }));
-    gBrowser.selectedTab = gBrowser.addTab();
+    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
     gBrowser.loadURI(TESTROOT + "installtrigger.html?" + triggers);
     await progressPromise;
     let installDialog = await dialogPromise;
 
     let notificationPromise = waitForNotification("addon-installed");
     acceptInstallDialog(installDialog);
     await notificationPromise;
 
@@ -585,17 +585,17 @@ function test_allUnverified() {
     await removeTab();
   })();
 },
 
 function test_url() {
   return (async function() {
     let progressPromise = waitForProgressNotification();
     let dialogPromise = waitForInstallDialog();
-    gBrowser.selectedTab = gBrowser.addTab("about:blank");
+    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "about:blank");
     await BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser);
     gBrowser.loadURI(TESTROOT + "amosigned.xpi");
     await progressPromise;
     let installDialog = await dialogPromise;
 
     let notificationPromise = waitForNotification("addon-install-restart");
     acceptInstallDialog(installDialog);
     let panel = await notificationPromise;
@@ -626,17 +626,17 @@ function test_localFile() {
     }
 
     let failPromise = new Promise(resolve => {
       Services.obs.addObserver(function observer() {
         Services.obs.removeObserver(observer, "addon-install-failed");
         resolve();
       }, "addon-install-failed");
     });
-    gBrowser.selectedTab = gBrowser.addTab("about:blank");
+    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "about:blank");
     await BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser);
     gBrowser.loadURI(path);
     await failPromise;
 
     // Wait for the browser code to add the failure notification
     await waitForSingleNotification();
 
     let notification = PopupNotifications.panel.childNodes[0];
@@ -653,17 +653,17 @@ function test_tabClose() {
   return (async function() {
     if (!Preferences.get("xpinstall.customConfirmationUI", false)) {
       info("Test skipped due to xpinstall.customConfirmationUI being false.");
       return;
     }
 
     let progressPromise = waitForProgressNotification();
     let dialogPromise = waitForInstallDialog();
-    gBrowser.selectedTab = gBrowser.addTab("about:blank");
+    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "about:blank");
     await BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser);
     gBrowser.loadURI(TESTROOT + "amosigned.xpi");
     await progressPromise;
     await dialogPromise;
 
     let installs = await getInstalls();
     is(installs.length, 1, "Should be one pending install");
 
@@ -709,17 +709,17 @@ function test_tabNavigate() {
   })();
 },
 
 function test_urlBar() {
   return (async function() {
     let progressPromise = waitForProgressNotification();
     let dialogPromise = waitForInstallDialog();
 
-    gBrowser.selectedTab = gBrowser.addTab("about:blank");
+    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "about:blank");
     await BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser);
     gURLBar.value = TESTROOT + "amosigned.xpi";
     gURLBar.focus();
     EventUtils.synthesizeKey("VK_RETURN", {});
 
     await progressPromise;
     let installDialog = await dialogPromise;
 
@@ -739,17 +739,17 @@ function test_urlBar() {
 
     await removeTab();
   })();
 },
 
 function test_wrongHost() {
   return (async function() {
     let requestedUrl = TESTROOT2 + "enabled.html";
-    gBrowser.selectedTab = gBrowser.addTab();
+    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
 
     let loadedPromise = BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser, false, requestedUrl);
     gBrowser.loadURI(TESTROOT2 + "enabled.html");
     await loadedPromise;
 
     let progressPromise = waitForProgressNotification();
     let notificationPromise = waitForNotification("addon-install-failed");
     gBrowser.loadURI(TESTROOT + "corrupt.xpi");

--- a/browser/base/content/test/general/browser_bug555224.js
+++ b/browser/base/content/test/general/browser_bug555224.js
@@ -19,22 +19,22 @@ function testBackgroundLoad() {
 function testInitialZoom() {
   (async function() {
     is(ZoomManager.zoom, 1, "initial zoom level should be 1");
     FullZoom.enlarge();
 
     gTestZoom = ZoomManager.zoom;
     isnot(gTestZoom, 1, "zoom level should have changed");
 
-    gBgTab = gBrowser.addTab();
+    gBgTab = BrowserTestUtils.addTab(gBrowser);
     await FullZoomHelper.load(gBgTab, "http://mochi.test:8888" + TEST_PAGE);
   })().then(testBackgroundLoad, FullZoomHelper.failAndContinue(finish));
 }
 
 function test() {
   waitForExplicitFinish();
 
   (async function() {
-    gTestTab = gBrowser.addTab();
+    gTestTab = BrowserTestUtils.addTab(gBrowser);
     await FullZoomHelper.selectTabAndWaitForLocationChange(gTestTab);
     await FullZoomHelper.load(gTestTab, "http://example.org" + TEST_PAGE);
   })().then(testInitialZoom, FullZoomHelper.failAndContinue(finish));
 }

--- a/browser/base/content/test/general/browser_bug555767.js
+++ b/browser/base/content/test/general/browser_bug555767.js
@@ -2,25 +2,25 @@
      * 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/. */
 
     add_task(async function() {
       let testURL = "http://example.org/browser/browser/base/content/test/general/dummy_page.html";
       let tabSelected = false;
 
       // Open the base tab
-      let baseTab = gBrowser.addTab(testURL);
+      let baseTab = BrowserTestUtils.addTab(gBrowser, testURL);
 
       // Wait for the tab to be fully loaded so matching happens correctly
       await promiseTabLoaded(baseTab);
       if (baseTab.linkedBrowser.currentURI.spec == "about:blank")
         return;
       baseTab.linkedBrowser.removeEventListener("load", arguments.callee, true);
 
-      let testTab = gBrowser.addTab();
+      let testTab = BrowserTestUtils.addTab(gBrowser);
 
       // Select the testTab
       gBrowser.selectedTab = testTab;
 
       // Set the urlbar to include the moz-action
       gURLBar.value = "moz-action:switchtab," + JSON.stringify({url: testURL});
       // Focus the urlbar so we can press enter
       gURLBar.focus();

--- a/browser/base/content/test/general/browser_bug559991.js
+++ b/browser/base/content/test/general/browser_bug559991.js
@@ -8,17 +8,17 @@ function test() {
   waitForExplicitFinish();
 
   gPrefService.setBoolPref("browser.zoom.updateBackgroundTabs", true);
   gPrefService.setBoolPref("browser.zoom.siteSpecific", true);
 
   let uri = "http://example.org/browser/browser/base/content/test/general/dummy_page.html";
 
   (async function() {
-    tab = gBrowser.addTab();
+    tab = BrowserTestUtils.addTab(gBrowser);
     await FullZoomHelper.load(tab, uri);
 
     // -------------------------------------------------------------------
     // Test - Trigger a tab switch that should update the zoom level
     await FullZoomHelper.selectTabAndWaitForLocationChange(tab);
     ok(true, "applyPrefToSetting was called");
   })().then(endTest, FullZoomHelper.failAndContinue(endTest));
 }

--- a/browser/base/content/test/general/browser_bug561636.js
+++ b/browser/base/content/test/general/browser_bug561636.js
@@ -35,17 +35,17 @@ function getDocFooter() {
 }
 
 function getEmptyFrame() {
   return "<iframe style='width:100px; height:30px; margin:3px; border:1px solid lightgray;' " +
          "name='t' srcdoc=\"<html><head><meta charset='utf-8'></head><body>form target</body></html>\"></iframe>";
 }
 
 async function openNewTab(uri, background) {
-  let tab = gBrowser.addTab();
+  let tab = BrowserTestUtils.addTab(gBrowser);
   let browser = gBrowser.getBrowserForTab(tab);
   if (!background) {
     gBrowser.selectedTab = tab;
   }
   await promiseTabLoadEvent(tab, "data:text/html," + escape(uri));
   return browser;
 }
 

--- a/browser/base/content/test/general/browser_bug563588.js
+++ b/browser/base/content/test/general/browser_bug563588.js
@@ -5,18 +5,18 @@ function press(key, expectedPos) {
      "accel+" + key + " doesn't change which tab is selected");
   is(gBrowser.tabContainer.selectedIndex, expectedPos,
      "accel+" + key + " moves the tab to the expected position");
   is(document.activeElement, gBrowser.selectedTab,
      "accel+" + key + " leaves the selected tab focused");
 }
 
 function test() {
-  gBrowser.addTab();
-  gBrowser.addTab();
+  BrowserTestUtils.addTab(gBrowser);
+  BrowserTestUtils.addTab(gBrowser);
   is(gBrowser.tabs.length, 3, "got three tabs");
   is(gBrowser.tabs[0], gBrowser.selectedTab, "first tab is selected");
 
   gBrowser.selectedTab.focus();
   is(document.activeElement, gBrowser.selectedTab, "selected tab is focused");
 
   press("right", 1);
   press("down", 2);

--- a/browser/base/content/test/general/browser_bug575561.js
+++ b/browser/base/content/test/general/browser_bug575561.js
@@ -59,17 +59,17 @@ var waitForTabOpen = async function() {
 
   await waitForDocLoadComplete(event.target.linkedBrowser);
   await Promise.resolve();
 
   gBrowser.removeCurrentTab();
 };
 
 var testLink = async function(aLinkIndexOrFunction, pinTab, expectNewTab, testSubFrame, aURL = TEST_URL) {
-  let appTab = gBrowser.addTab(aURL, {skipAnimation: true});
+  let appTab = BrowserTestUtils.addTab(gBrowser, aURL, {skipAnimation: true});
   if (pinTab)
     gBrowser.pinTab(appTab);
   gBrowser.selectedTab = appTab;
 
   await waitForDocLoadComplete();
 
   let browser = appTab.linkedBrowser;
   if (testSubFrame)

--- a/browser/base/content/test/general/browser_bug575830.js
+++ b/browser/base/content/test/general/browser_bug575830.js
@@ -5,18 +5,18 @@
 
 function test() {
   let tab1, tab2;
   const TEST_IMAGE = "http://example.org/browser/browser/base/content/test/general/moz.png";
 
   waitForExplicitFinish();
 
   (async function() {
-    tab1 = gBrowser.addTab();
-    tab2 = gBrowser.addTab();
+    tab1 = BrowserTestUtils.addTab(gBrowser);
+    tab2 = BrowserTestUtils.addTab(gBrowser);
     await FullZoomHelper.selectTabAndWaitForLocationChange(tab1);
     await FullZoomHelper.load(tab1, TEST_IMAGE);
 
     is(ZoomManager.zoom, 1, "initial zoom level for first should be 1");
 
     FullZoom.enlarge();
     let zoom = ZoomManager.zoom;
     isnot(zoom, 1, "zoom level should have changed");

--- a/browser/base/content/test/general/browser_bug577121.js
+++ b/browser/base/content/test/general/browser_bug577121.js
@@ -5,18 +5,18 @@
 function test() {
   Services.prefs.setBoolPref("toolkit.cosmeticAnimations.enabled", false);
   registerCleanupFunction(function() {
     Services.prefs.clearUserPref("toolkit.cosmeticAnimations.enabled");
   });
 
   // Open 2 other tabs, and pin the second one. Like that, the initial tab
   // should get closed.
-  let testTab1 = gBrowser.addTab();
-  let testTab2 = gBrowser.addTab();
+  let testTab1 = BrowserTestUtils.addTab(gBrowser);
+  let testTab2 = BrowserTestUtils.addTab(gBrowser);
   gBrowser.pinTab(testTab2);
 
   // Now execute "Close other Tabs" on the first manually opened tab (tab1).
   // -> tab2 ist pinned, tab1 should remain open and the initial tab should
   // get closed.
   gBrowser.removeAllTabsBut(testTab1);
 
   is(gBrowser.tabs.length, 2, "there are two remaining tabs open");

--- a/browser/base/content/test/general/browser_bug579872.js
+++ b/browser/base/content/test/general/browser_bug579872.js
@@ -1,14 +1,14 @@
 /* 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/. */
 
 function test() {
-  let newTab = gBrowser.addTab();
+  let newTab = BrowserTestUtils.addTab(gBrowser);
   waitForExplicitFinish();
   BrowserTestUtils.browserLoaded(newTab.linkedBrowser).then(mainPart);
 
   function mainPart() {
     gBrowser.pinTab(newTab);
     gBrowser.selectedTab = newTab;
 
     openUILinkIn("javascript:var x=0;", "current");

--- a/browser/base/content/test/general/browser_bug580638.js
+++ b/browser/base/content/test/general/browser_bug580638.js
@@ -23,17 +23,17 @@ function test() {
     }
   }
 
   let lastSelectedTab = gBrowser.selectedTab;
   ok(!lastSelectedTab.pinned, "We should have started with a regular tab selected");
 
   testState(false);
 
-  let pinnedTab = gBrowser.addTab("about:blank");
+  let pinnedTab = BrowserTestUtils.addTab(gBrowser, "about:blank");
   gBrowser.pinTab(pinnedTab);
 
   // Just pinning the tab shouldn't change the key state.
   testState(false);
 
   // Test updating key state after selecting a tab.
   gBrowser.selectedTab = pinnedTab;
   testState(true);

--- a/browser/base/content/test/general/browser_bug580956.js
+++ b/browser/base/content/test/general/browser_bug580956.js
@@ -10,17 +10,17 @@ function isUndoCloseEnabled() {
 function test() {
   waitForExplicitFinish();
 
   gPrefService.setIntPref("browser.sessionstore.max_tabs_undo", 0);
   gPrefService.clearUserPref("browser.sessionstore.max_tabs_undo");
   is(numClosedTabs(), 0, "There should be 0 closed tabs.");
   ok(!isUndoCloseEnabled(), "Undo Close Tab should be disabled.");
 
-  var tab = gBrowser.addTab("http://mochi.test:8888/");
+  var tab = BrowserTestUtils.addTab(gBrowser, "http://mochi.test:8888/");
   var browser = gBrowser.getBrowserForTab(tab);
   BrowserTestUtils.browserLoaded(browser).then(() => {
     BrowserTestUtils.removeTab(tab).then(() => {
       ok(isUndoCloseEnabled(), "Undo Close Tab should be enabled.");
       finish();
     });
   });
 }

--- a/browser/base/content/test/general/browser_bug581242.js
+++ b/browser/base/content/test/general/browser_bug581242.js
@@ -1,15 +1,15 @@
 /* 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/. */
 
 function test() {
   // Create a new tab and load about:addons
-  let blanktab = gBrowser.addTab();
+  let blanktab = BrowserTestUtils.addTab(gBrowser);
   gBrowser.selectedTab = blanktab;
   BrowserOpenAddonsMgr();
 
   is(blanktab, gBrowser.selectedTab, "Current tab should be blank tab");
   // Verify that about:addons loads
   waitForExplicitFinish();
   gBrowser.selectedBrowser.addEventListener("load", function() {
     let browser = blanktab.linkedBrowser;

--- a/browser/base/content/test/general/browser_bug581253.js
+++ b/browser/base/content/test/general/browser_bug581253.js
@@ -10,17 +10,17 @@ function test() {
   registerCleanupFunction(function() {
     PlacesUtils.bookmarks.removeFolderChildren(PlacesUtils.unfiledBookmarksFolderId);
     if (timerID > 0) {
       clearTimeout(timerID);
     }
   });
   waitForExplicitFinish();
 
-  let tab = gBrowser.selectedTab = gBrowser.addTab();
+  let tab = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
   tab.linkedBrowser.addEventListener("load", (function(event) {
     let uri = makeURI(testURL);
     let bmTxn =
       new PlacesCreateBookmarkTransaction(uri,
                                           PlacesUtils.unfiledBookmarksFolderId,
                                           -1, "", null, []);
     PlacesUtils.transactionManager.doTransaction(bmTxn);
 

--- a/browser/base/content/test/general/browser_bug585785.js
+++ b/browser/base/content/test/general/browser_bug585785.js
@@ -1,14 +1,14 @@
 var tab;
 
 function test() {
   waitForExplicitFinish();
 
-  tab = gBrowser.addTab();
+  tab = BrowserTestUtils.addTab(gBrowser);
   isnot(tab.getAttribute("fadein"), "true", "newly opened tab is yet to fade in");
 
   // Try to remove the tab right before the opening animation's first frame
   window.requestAnimationFrame(checkAnimationState);
 }
 
 function checkAnimationState() {
   is(tab.getAttribute("fadein"), "true", "tab opening animation initiated");

--- a/browser/base/content/test/general/browser_bug585830.js
+++ b/browser/base/content/test/general/browser_bug585830.js
@@ -1,16 +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/. */
 
 function test() {
   let tab1 = gBrowser.selectedTab;
-  let tab2 = gBrowser.addTab("about:blank", {skipAnimation: true});
-  gBrowser.addTab();
+  let tab2 = BrowserTestUtils.addTab(gBrowser, "about:blank", {skipAnimation: true});
+  BrowserTestUtils.addTab(gBrowser);
   gBrowser.selectedTab = tab2;
 
   gBrowser.removeCurrentTab({animate: true});
   gBrowser.tabContainer.advanceSelectedTab(-1, true);
   is(gBrowser.selectedTab, tab1, "First tab should be selected");
   gBrowser.removeTab(tab2);
 
   // test for "null has no properties" fix. See Bug 585830 Comment 13

--- a/browser/base/content/test/general/browser_bug592338.js
+++ b/browser/base/content/test/general/browser_bug592338.js
@@ -35,17 +35,17 @@ function promisePopupNotificationShown(n
 
 var TESTS = [
 function test_install_http() {
   is(LightweightThemeManager.currentTheme, null, "Should be no lightweight theme selected");
 
   var pm = Services.perms;
   pm.add(makeURI("http://example.org/"), "install", pm.ALLOW_ACTION);
 
-  gBrowser.selectedTab = gBrowser.addTab("http://example.org/browser/browser/base/content/test/general/bug592338.html");
+  gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "http://example.org/browser/browser/base/content/test/general/bug592338.html");
   gBrowser.selectedBrowser.addEventListener("pageshow", function() {
     if (gBrowser.contentDocument.location.href == "about:blank")
       return;
 
     gBrowser.selectedBrowser.removeEventListener("pageshow", arguments.callee);
 
     executeSoon(function() {
       BrowserTestUtils.synthesizeMouse("#theme-install", 2, 2, {}, gBrowser.selectedBrowser);
@@ -62,17 +62,17 @@ function test_install_http() {
 },
 
 function test_install_lwtheme() {
   is(LightweightThemeManager.currentTheme, null, "Should be no lightweight theme selected");
 
   var pm = Services.perms;
   pm.add(makeURI("https://example.com/"), "install", pm.ALLOW_ACTION);
 
-  gBrowser.selectedTab = gBrowser.addTab("https://example.com/browser/browser/base/content/test/general/bug592338.html");
+  gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "https://example.com/browser/browser/base/content/test/general/bug592338.html");
   gBrowser.selectedBrowser.addEventListener("pageshow", function() {
     if (gBrowser.contentDocument.location.href == "about:blank")
       return;
 
     gBrowser.selectedBrowser.removeEventListener("pageshow", arguments.callee);
 
     let promise = promisePopupNotificationShown("addon-installed");
     BrowserTestUtils.synthesizeMouse("#theme-install", 2, 2, {}, gBrowser.selectedBrowser);

--- a/browser/base/content/test/general/browser_bug594131.js
+++ b/browser/base/content/test/general/browser_bug594131.js
@@ -1,14 +1,14 @@
 /* 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/. */
 
 function test() {
-  let newTab = gBrowser.addTab("http://example.com");
+  let newTab = BrowserTestUtils.addTab(gBrowser, "http://example.com");
   waitForExplicitFinish();
   BrowserTestUtils.browserLoaded(newTab.linkedBrowser).then(mainPart);
 
   function mainPart() {
     gBrowser.pinTab(newTab);
     gBrowser.selectedTab = newTab;
 
     openUILinkIn("http://example.org/", "current", { inBackground: true });

--- a/browser/base/content/test/general/browser_bug595507.js
+++ b/browser/base/content/test/general/browser_bug595507.js
@@ -3,17 +3,17 @@
  */
 add_task(async function() {
   let uri = "<iframe src=\"data:text/html,<iframe name='t'></iframe><form target='t' action='data:text/html,'><input required id='i'><input id='s' type='submit'></form>\"</iframe>";
 
   var gInvalidFormPopup = document.getElementById("invalid-form-popup");
   ok(gInvalidFormPopup,
      "The browser should have a popup to show when a form is invalid");
 
-  let tab = gBrowser.addTab();
+  let tab = BrowserTestUtils.addTab(gBrowser);
   let browser = gBrowser.getBrowserForTab(tab);
   gBrowser.selectedTab = tab;
 
   await promiseTabLoadEvent(tab, "data:text/html," + escape(uri));
 
   let popupShownPromise = promiseWaitForEvent(gInvalidFormPopup, "popupshown");
 
   await ContentTask.spawn(browser, {}, async function() {

--- a/browser/base/content/test/general/browser_bug624734.js
+++ b/browser/base/content/test/general/browser_bug624734.js
@@ -11,17 +11,17 @@ function finishTest() {
 
   gBrowser.removeCurrentTab();
   finish();
 }
 
 function test() {
   waitForExplicitFinish();
 
-  let tab = gBrowser.selectedTab = gBrowser.addTab();
+  let tab = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
   BrowserTestUtils.browserLoaded(tab.linkedBrowser).then(() => {
     if (BookmarkingUI.status == BookmarkingUI.STATUS_UPDATING) {
       waitForCondition(() => BookmarkingUI.status != BookmarkingUI.STATUS_UPDATING, finishTest, "BookmarkingUI was updating for too long");
     } else {
       finishTest();
     }
   });
 

--- a/browser/base/content/test/general/browser_bug655584.js
+++ b/browser/base/content/test/general/browser_bug655584.js
@@ -1,17 +1,17 @@
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
 // Bug 655584 - awesomebar suggestions don't update after tab is closed
 
 add_task(async function() {
-  var tab1 = gBrowser.addTab();
-  var tab2 = gBrowser.addTab();
+  var tab1 = BrowserTestUtils.addTab(gBrowser);
+  var tab2 = BrowserTestUtils.addTab(gBrowser);
 
   // When urlbar in a new tab is focused, and a tab switch occurs,
   // the urlbar popup should be closed
   await BrowserTestUtils.switchTab(gBrowser, tab2);
   gURLBar.focus(); // focus the urlbar in the tab we will switch to
   await BrowserTestUtils.switchTab(gBrowser, tab1);
   gURLBar.openPopup();
   await BrowserTestUtils.switchTab(gBrowser, tab2);

--- a/browser/base/content/test/general/browser_bug664672.js
+++ b/browser/base/content/test/general/browser_bug664672.js
@@ -1,12 +1,12 @@
 function test() {
   waitForExplicitFinish();
 
-  var tab = gBrowser.addTab();
+  var tab = BrowserTestUtils.addTab(gBrowser);
 
   tab.addEventListener("TabClose", function() {
     ok(tab.linkedBrowser, "linkedBrowser should still exist during the TabClose event");
 
     executeSoon(function() {
       ok(!tab.linkedBrowser, "linkedBrowser should be gone after the TabClose event");
 
       finish();

--- a/browser/base/content/test/general/browser_bug678392.js
+++ b/browser/base/content/test/general/browser_bug678392.js
@@ -155,17 +155,17 @@ function test2() {
   // Test growing of snapshot array across tabs.
   let tab = gBrowser.selectedTab;
 
   load(tab, HTTPROOT + "browser_bug678392-1.html", function() {
     load(tab, HTTPROOT + "browser_bug678392-2.html", function() {
       is(gHistorySwipeAnimation._trackedSnapshots.length, 2, "Length of " +
          "snapshot array is equal to 2 after loading two pages");
       let prevTab = tab;
-      tab = gBrowser.addTab("about:newtab");
+      tab = BrowserTestUtils.addTab(gBrowser, "about:newtab");
       gBrowser.selectedTab = tab;
       load(tab, HTTPROOT + "browser_bug678392-2.html" /* initial page */,
            function() {
         load(tab, HTTPROOT + "browser_bug678392-1.html", function() {
           load(tab, HTTPROOT + "browser_bug678392-2.html", function() {
             is(gHistorySwipeAnimation._trackedSnapshots.length, 4, "Length " +
                "of snapshot array is equal to 4 after loading two pages in " +
                "two tabs each.");

--- a/browser/base/content/test/general/browser_bug719271.js
+++ b/browser/base/content/test/general/browser_bug719271.js
@@ -7,18 +7,18 @@ const TEST_PAGE = "http://example.org/br
 const TEST_VIDEO = "http://example.org/browser/browser/base/content/test/general/video.ogg";
 
 var gTab1, gTab2, gLevel1;
 
 function test() {
   waitForExplicitFinish();
 
   (async function() {
-    gTab1 = gBrowser.addTab();
-    gTab2 = gBrowser.addTab();
+    gTab1 = BrowserTestUtils.addTab(gBrowser);
+    gTab2 = BrowserTestUtils.addTab(gBrowser);
 
     await FullZoomHelper.selectTabAndWaitForLocationChange(gTab1);
     await FullZoomHelper.load(gTab1, TEST_PAGE);
     await FullZoomHelper.load(gTab2, TEST_VIDEO);
   })().then(zoomTab1, FullZoomHelper.failAndContinue(finish));
 }
 
 function zoomTab1() {

--- a/browser/base/content/test/general/browser_bug749738.js
+++ b/browser/base/content/test/general/browser_bug749738.js
@@ -4,17 +4,17 @@
 
 "use strict";
 
 const DUMMY_PAGE = "http://example.org/browser/browser/base/content/test/general/dummy_page.html";
 
 function test() {
   waitForExplicitFinish();
 
-  let tab = gBrowser.addTab();
+  let tab = BrowserTestUtils.addTab(gBrowser);
   gBrowser.selectedTab = tab;
 
   BrowserTestUtils.loadURI(tab.linkedBrowser, DUMMY_PAGE);
   BrowserTestUtils.browserLoaded(tab.linkedBrowser).then(() => {
     gFindBar.onFindCommand();
     EventUtils.sendString("Dummy");
     gBrowser.removeTab(tab);
 

--- a/browser/base/content/test/general/browser_bug817947.js
+++ b/browser/base/content/test/general/browser_bug817947.js
@@ -26,23 +26,23 @@ function test() {
         win.close();
         finish();
       });
     });
   });
 }
 
 function preparePendingTab(aCallback) {
-  let tab = gBrowser.addTab(URL);
+  let tab = BrowserTestUtils.addTab(gBrowser, URL);
 
   whenLoaded(tab.linkedBrowser, function() {
     BrowserTestUtils.removeTab(tab).then(() => {
       let [{state}] = JSON.parse(SessionStore.getClosedTabData(window));
 
-      tab = gBrowser.addTab("about:blank");
+      tab = BrowserTestUtils.addTab(gBrowser, "about:blank");
       whenLoaded(tab.linkedBrowser, function() {
         SessionStore.setTabState(tab, JSON.stringify(state));
         ok(tab.hasAttribute("pending"), "tab should be pending");
         aCallback(tab);
       });
     });
   });
 }

--- a/browser/base/content/test/general/browser_clipboard.js
+++ b/browser/base/content/test/general/browser_clipboard.js
@@ -2,17 +2,17 @@
 // types (html and images) are copied to and pasted from the clipboard properly.
 
 var testPage = "<body style='margin: 0'>" +
                "  <img id='img' tabindex='1' src='http://example.org/browser/browser/base/content/test/general/moz.png'>" +
                "  <div id='main' contenteditable='true'>Test <b>Bold</b> After Text</div>" +
                "</body>";
 
 add_task(async function() {
-  let tab = gBrowser.addTab();
+  let tab = BrowserTestUtils.addTab(gBrowser);
   let browser = gBrowser.getBrowserForTab(tab);
 
   gBrowser.selectedTab = tab;
 
   await promiseTabLoadEvent(tab, "data:text/html," + escape(testPage));
   await SimpleTest.promiseFocus(browser.contentWindowAsCPOW);
 
   const modifier = (navigator.platform.indexOf("Mac") >= 0) ?

--- a/browser/base/content/test/general/browser_ctrlTab.js
+++ b/browser/base/content/test/general/browser_ctrlTab.js
@@ -1,14 +1,14 @@
 add_task(async function() {
   gPrefService.setBoolPref("browser.ctrlTab.previews", true);
 
-  gBrowser.addTab();
-  gBrowser.addTab();
-  gBrowser.addTab();
+  BrowserTestUtils.addTab(gBrowser);
+  BrowserTestUtils.addTab(gBrowser);
+  BrowserTestUtils.addTab(gBrowser);
 
   checkTabs(4);
 
   await ctrlTabTest([2], 1, 0);
   await ctrlTabTest([2, 3, 1], 2, 2);
   await ctrlTabTest([], 4, 2);
 
   {
@@ -32,17 +32,17 @@ add_task(async function() {
     let tabs = gBrowser.tabs.length;
     await pressCtrlTab();
     await pressCtrlTab(true);
     await synthesizeCtrlW();
     is(gBrowser.tabs.length, tabs - 1, "Ctrl+Tab -> Ctrl+W removes the selected tab");
     await releaseCtrl();
   }
 
-  gBrowser.addTab();
+  BrowserTestUtils.addTab(gBrowser);
   checkTabs(3);
   await ctrlTabTest([2, 1, 0], 7, 1);
 
   { // test for bug 1292049
     let tabToClose = await BrowserTestUtils.openNewForegroundTab(gBrowser, "about:buildconfig");
     checkTabs(4);
     selectTabs([0, 1, 2, 3]);
 

--- a/browser/base/content/test/general/browser_discovery.js
+++ b/browser/base/content/test/general/browser_discovery.js
@@ -8,17 +8,17 @@ function setHandlerFunc(aResultFunc) {
   gBrowser.addEventListener("DOMLinkAdded", function(event) {
     executeSoon(aResultFunc);
   }, {once: true});
 }
 
 function test() {
   waitForExplicitFinish();
 
-  gBrowser.selectedTab = gBrowser.addTab();
+  gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
   browser = gBrowser.selectedBrowser;
   browser.addEventListener("load", function(event) {
     iconDiscovery();
   }, {capture: true, once: true});
   var rootDir = getRootDirectory(gTestPath);
   content.location = rootDir + "discovery.html";
 }
 

--- a/browser/base/content/test/general/browser_domFullscreen_fullscreenMode.js
+++ b/browser/base/content/test/general/browser_domFullscreen_fullscreenMode.js
@@ -141,17 +141,17 @@ function checkState(expectedStates, cont
 const kPage = "http://example.org/browser/browser/" +
               "base/content/test/general/dummy_page.html";
 
 add_task(async function() {
   await pushPrefs(
     ["full-screen-api.transition-duration.enter", "0 0"],
     ["full-screen-api.transition-duration.leave", "0 0"]);
 
-  let tab = gBrowser.addTab(kPage);
+  let tab = BrowserTestUtils.addTab(gBrowser, kPage);
   let browser = tab.linkedBrowser;
   gBrowser.selectedTab = tab;
   await waitForDocLoadComplete();
 
   registerCleanupFunction(() => {
     if (browser.contentWindow.fullScreen) {
       BrowserFullScreen();
     }

--- a/browser/base/content/test/general/browser_double_close_tab.js
+++ b/browser/base/content/test/general/browser_double_close_tab.js
@@ -32,17 +32,17 @@ function waitForDialogDestroyed(node, ca
     clearTimeout(failureTimeout);
     observer.disconnect();
     observer = null;
     callback();
   }
 }
 
 add_task(async function() {
-  testTab = gBrowser.selectedTab = gBrowser.addTab();
+  testTab = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
   await promiseTabLoadEvent(testTab, TEST_PAGE);
   // XXXgijs the reason this has nesting and callbacks rather than promises is
   // that DOM promises resolve on the next tick. So they're scheduled
   // in an event queue. So when we spin a new event queue for a modal dialog...
   // everything gets messed up and the promise's .then callbacks never get
   // called, despite resolve() being called just fine.
   await new Promise(resolveOuter => {
     waitForDialog(dialogNode => {

--- a/browser/base/content/test/general/browser_drag.js
+++ b/browser/base/content/test/general/browser_drag.js
@@ -26,17 +26,17 @@ function test() {
   var dt = EventUtils.synthesizeDragStart(document.getElementById("identity-box"), expected);
   is(dt, null, "drag on proxy icon");
   gURLBar.setAttribute("pageproxystate", oldstate);
   // Now, the identity information panel is opened by the proxy icon click.
   // We need to close it for next tests.
   EventUtils.synthesizeKey("VK_ESCAPE", {}, window);
 
   // now test dragging onto a tab
-  var tab = gBrowser.addTab("about:blank", {skipAnimation: true});
+  var tab = BrowserTestUtils.addTab(gBrowser, "about:blank", {skipAnimation: true});
   var browser = gBrowser.getBrowserForTab(tab);
 
   browser.addEventListener("load", function() {
     is(browser.contentWindow.location, "http://mochi.test:8888/", "drop on tab");
     gBrowser.removeTab(tab);
     finish();
   }, true);
 

--- a/browser/base/content/test/general/browser_e10s_chrome_process.js
+++ b/browser/base/content/test/general/browser_e10s_chrome_process.js
@@ -36,17 +36,17 @@ const CHROME_PROCESS = Ci.nsIXULRuntime.
 const CONTENT_PROCESS = Ci.nsIXULRuntime.PROCESS_TYPE_CONTENT;
 const PATH = (getRootDirectory(gTestPath) + "test_process_flags_chrome.html").replace("chrome://mochitests", "");
 
 const CHROME = "chrome://mochitests" + PATH;
 const CANREMOTE = "chrome://mochitests-any" + PATH;
 const MUSTREMOTE = "chrome://mochitests-content" + PATH;
 
 add_task(async function init() {
-  gBrowser.selectedTab = gBrowser.addTab("about:blank");
+  gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "about:blank");
 });
 
 registerCleanupFunction(() => {
   gBrowser.removeCurrentTab();
 });
 
 function test_url(url, chromeResult, contentResult) {
   is(E10SUtils.canLoadURIInProcess(url, CHROME_PROCESS),

--- a/browser/base/content/test/general/browser_e10s_switchbrowser.js
+++ b/browser/base/content/test/general/browser_e10s_switchbrowser.js
@@ -111,17 +111,17 @@ var forward = async function() {
 
 // Tests that navigating from a page that should be in the remote process and
 // a page that should be in the main process works and retains history
 add_task(async function test_navigation() {
   let expectedRemote = gMultiProcessBrowser;
 
   info("1");
   // Create a tab and load a remote page in it
-  gBrowser.selectedTab = gBrowser.addTab("about:blank", {skipAnimation: true});
+  gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "about:blank", {skipAnimation: true});
   let {permanentKey} = gBrowser.selectedBrowser;
   await waitForLoad("http://example.org/" + DUMMY_PATH);
   is(gBrowser.selectedBrowser.isRemoteBrowser, expectedRemote, "Remote attribute should be correct");
   is(gBrowser.selectedBrowser.permanentKey, permanentKey, "browser.permanentKey is still the same");
 
   info("2");
   // Load another page
   await waitForLoad("http://example.com/" + DUMMY_PATH);
@@ -188,17 +188,17 @@ add_task(async function test_navigation(
 
 // Tests that calling gBrowser.loadURI or browser.loadURI to load a page in a
 // different process updates the browser synchronously
 add_task(async function test_synchronous() {
   let expectedRemote = gMultiProcessBrowser;
 
   info("1");
   // Create a tab and load a remote page in it
-  gBrowser.selectedTab = gBrowser.addTab("about:blank", {skipAnimation: true});
+  gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "about:blank", {skipAnimation: true});
   let {permanentKey} = gBrowser.selectedBrowser;
   await waitForLoad("http://example.org/" + DUMMY_PATH);
   is(gBrowser.selectedBrowser.isRemoteBrowser, expectedRemote, "Remote attribute should be correct");
   is(gBrowser.selectedBrowser.permanentKey, permanentKey, "browser.permanentKey is still the same");
 
   info("2");
   // Load another page
   info("Loading about:robots");
@@ -228,17 +228,17 @@ add_task(async function test_synchronous
 
 // Tests that load flags are correctly passed through to the child process with
 // normal loads
 add_task(async function test_loadflags() {
   let expectedRemote = gMultiProcessBrowser;
 
   info("1");
   // Create a tab and load a remote page in it
-  gBrowser.selectedTab = gBrowser.addTab("about:blank", {skipAnimation: true});
+  gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "about:blank", {skipAnimation: true});
   await waitForLoadWithFlags("about:robots");
   is(gBrowser.selectedBrowser.isRemoteBrowser, false, "Remote attribute should be correct");
   await check_history();
 
   info("2");
   // Load a page in the remote process with some custom flags
   await waitForLoadWithFlags("http://example.com/" + DUMMY_PATH, Ci.nsIWebNavigation.LOAD_FLAGS_BYPASS_HISTORY);
   is(gBrowser.selectedBrowser.isRemoteBrowser, expectedRemote, "Remote attribute should be correct");

--- a/browser/base/content/test/general/browser_favicon_change.js
+++ b/browser/base/content/test/general/browser_favicon_change.js
@@ -1,17 +1,17 @@
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/ */
 
 "use strict";
 
 const TEST_URL = "http://mochi.test:8888/browser/browser/base/content/test/general/file_favicon_change.html"
 
 add_task(async function() {
-  let extraTab = gBrowser.selectedTab = gBrowser.addTab();
+  let extraTab = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
   extraTab.linkedBrowser.loadURI(TEST_URL);
   let tabLoaded = BrowserTestUtils.browserLoaded(extraTab.linkedBrowser);
   let expectedFavicon = "http://example.org/one-icon";
   let haveChanged = new Promise.defer();
   let observer = new MutationObserver(function(mutations) {
     for (let mut of mutations) {
       if (mut.attributeName != "image") {
         continue;

--- a/browser/base/content/test/general/browser_favicon_change_not_in_document.js
+++ b/browser/base/content/test/general/browser_favicon_change_not_in_document.js
@@ -1,14 +1,14 @@
 "use strict";
 
 const TEST_URL = "http://mochi.test:8888/browser/browser/base/content/test/general/file_favicon_change_not_in_document.html"
 
 add_task(async function() {
-  let extraTab = gBrowser.selectedTab = gBrowser.addTab();
+  let extraTab = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
   let tabLoaded = promiseTabLoaded(extraTab);
   extraTab.linkedBrowser.loadURI(TEST_URL);
   let expectedFavicon = "http://example.org/one-icon";
   let haveChanged = new Promise.defer();
   let observer = new MutationObserver(function(mutations) {
     for (let mut of mutations) {
       if (mut.attributeName != "image") {
         continue;

--- a/browser/base/content/test/general/browser_feed_discovery.js
+++ b/browser/base/content/test/general/browser_feed_discovery.js
@@ -1,15 +1,15 @@
 const URL = "http://mochi.test:8888/browser/browser/base/content/test/general/feed_discovery.html"
 
 /** Test for Bug 377611 **/
 
 add_task(async function() {
   // Open a new tab.
-  gBrowser.selectedTab = gBrowser.addTab(URL);
+  gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, URL);
   registerCleanupFunction(() => gBrowser.removeCurrentTab());
 
   let browser = gBrowser.selectedBrowser;
   await BrowserTestUtils.browserLoaded(browser);
 
   let discovered = browser.feeds;
   ok(discovered.length > 0, "some feeds should be discovered");
 

--- a/browser/base/content/test/general/browser_findbarClose.js
+++ b/browser/base/content/test/general/browser_findbarClose.js
@@ -2,17 +2,17 @@
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
 // Tests find bar auto-close behavior
 
 var newTab;
 
 add_task(async function findbar_test() {
   waitForExplicitFinish();
-  newTab = gBrowser.addTab("about:blank");
+  newTab = BrowserTestUtils.addTab(gBrowser, "about:blank");
 
   let promise = ContentTask.spawn(newTab.linkedBrowser, null, async function() {
     await ContentTaskUtils.waitForEvent(this, "DOMContentLoaded", false);
   });
   newTab.linkedBrowser.loadURI("http://example.com/browser/" +
     "browser/base/content/test/general/test_bug628179.html");
   await promise;
 

--- a/browser/base/content/test/general/browser_fullscreen-window-open.js
+++ b/browser/base/content/test/general/browser_fullscreen-window-open.js
@@ -11,17 +11,17 @@ const TEST_FILE = "file_fullscreen-windo
 const gHttpTestRoot = getRootDirectory(gTestPath).replace("chrome://mochitests/content/",
                                                           "http://127.0.0.1:8888/");
 
 function test() {
   waitForExplicitFinish();
 
   Services.prefs.setBoolPref(PREF_DISABLE_OPEN_NEW_WINDOW, true);
 
-  let newTab = gBrowser.addTab(gHttpTestRoot + TEST_FILE);
+  let newTab = BrowserTestUtils.addTab(gBrowser, gHttpTestRoot + TEST_FILE);
   gBrowser.selectedTab = newTab;
 
   whenTabLoaded(newTab, function() {
     // Enter browser fullscreen mode.
     BrowserFullScreen();
 
     runNextTest();
   });

--- a/browser/base/content/test/general/browser_gZipOfflineChild.js
+++ b/browser/base/content/test/general/browser_gZipOfflineChild.js
@@ -63,17 +63,17 @@ function handleMessageEvents(event) {
 }
 
 function test() {
   waitForExplicitFinish();
 
   Services.prefs.setBoolPref("offline-apps.allow_by_default", true);
 
   // Open a new tab.
-  gBrowser.selectedTab = gBrowser.addTab(URL);
+  gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, URL);
   registerCleanupFunction(() => gBrowser.removeCurrentTab());
 
   BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser).then(() => {
     let window = gBrowser.selectedBrowser.contentWindow;
 
     window.addEventListener("message", handleMessageEvents);
   });
 }

--- a/browser/base/content/test/general/browser_gestureSupport.js
+++ b/browser/base/content/test/general/browser_gestureSupport.js
@@ -636,13 +636,13 @@ function test_rotateGesturesOnTab() {
   }
 
   gBrowser.removeTab(test_imageTab);
   test_imageTab = null;
   finish();
 }
 
 function test_rotateGestures() {
-  test_imageTab = gBrowser.addTab("chrome://branding/content/about-logo.png");
+  test_imageTab = BrowserTestUtils.addTab(gBrowser, "chrome://branding/content/about-logo.png");
   gBrowser.selectedTab = test_imageTab;
 
   gBrowser.selectedBrowser.addEventListener("load", test_rotateGesturesOnTab, true);
 }

--- a/browser/base/content/test/general/browser_hide_removing.js
+++ b/browser/base/content/test/general/browser_hide_removing.js
@@ -3,17 +3,17 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // Bug 587922: tabs don't get removed if they're hidden
 
 function test() {
   waitForExplicitFinish();
 
   // Add a tab that will get removed and hidden
-  let testTab = gBrowser.addTab("about:blank", {skipAnimation: true});
+  let testTab = BrowserTestUtils.addTab(gBrowser, "about:blank", {skipAnimation: true});
   is(gBrowser.visibleTabs.length, 2, "just added a tab, so 2 tabs");
   gBrowser.selectedTab = testTab;
 
   let numVisBeforeHide, numVisAfterHide;
   gBrowser.tabContainer.addEventListener("TabSelect", function() {
     // While the next tab is being selected, hide the removing tab
     numVisBeforeHide = gBrowser.visibleTabs.length;
     gBrowser.hideTab(testTab);

--- a/browser/base/content/test/general/browser_keywordBookmarklets.js
+++ b/browser/base/content/test/general/browser_keywordBookmarklets.js
@@ -1,15 +1,15 @@
 "use strict"
 
 add_task(async function test_keyword_bookmarklet() {
   let bm = await PlacesUtils.bookmarks.insert({ parentGuid: PlacesUtils.bookmarks.unfiledGuid,
                                                 title: "bookmarklet",
                                                 url: "javascript:'1';" });
-  let tab = gBrowser.selectedTab = gBrowser.addTab();
+  let tab = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
   registerCleanupFunction(async function() {
     gBrowser.removeTab(tab);
     await PlacesUtils.bookmarks.remove(bm);
   });
   await promisePageShow();
   let originalPrincipal = gBrowser.contentPrincipal;
 
   function getPrincipalURI() {

--- a/browser/base/content/test/general/browser_keywordSearch.js
+++ b/browser/base/content/test/general/browser_keywordSearch.js
@@ -29,17 +29,17 @@ function test() {
         }, {once: true});
         executeSoon(finish);
       }
     }
   };
 
   Services.ww.registerNotification(windowObserver);
 
-  let tab = gBrowser.selectedTab = gBrowser.addTab();
+  let tab = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
 
   let listener = {
     onStateChange: function onLocationChange(webProgress, req, flags, status) {
       // Only care about document starts
       let docStart = Ci.nsIWebProgressListener.STATE_IS_DOCUMENT |
                      Ci.nsIWebProgressListener.STATE_START;
       if (!(flags & docStart))
         return;

--- a/browser/base/content/test/general/browser_keywordSearch_postData.js
+++ b/browser/base/content/test/general/browser_keywordSearch_postData.js
@@ -14,17 +14,17 @@ var gTests = [
     testText: "?   foo  ",
     expectText: "foo"
   }
 ];
 
 function test() {
   waitForExplicitFinish();
 
-  let tab = gBrowser.selectedTab = gBrowser.addTab();
+  let tab = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
 
   let searchObserver = function search_observer(aSubject, aTopic, aData) {
     let engine = aSubject.QueryInterface(Ci.nsISearchEngine);
     info("Observer: " + aData + " for " + engine.name);
 
     if (aData != "engine-added")
       return;
 

--- a/browser/base/content/test/general/browser_lastAccessedTab.js
+++ b/browser/base/content/test/general/browser_lastAccessedTab.js
@@ -21,17 +21,17 @@ function test() {
   waitForExplicitFinish();
 
   originalTab = gBrowser.selectedTab;
   nextStep(step2);
 }
 
 function step2() {
   isCurrent(originalTab, "selected tab has the current timestamp");
-  newTab = gBrowser.addTab("about:blank", {skipAnimation: true});
+  newTab = BrowserTestUtils.addTab(gBrowser, "about:blank", {skipAnimation: true});
   nextStep(step3);
 }
 
 function step3() {
   ok(newTab.lastAccessed < Date.now(), "new tab hasn't been selected so far");
   gBrowser.selectedTab = newTab;
   isCurrent(newTab, "new tab has the current timestamp after being selected");
   nextStep(step4);

--- a/browser/base/content/test/general/browser_offlineQuotaNotification.js
+++ b/browser/base/content/test/general/browser_offlineQuotaNotification.js
@@ -31,17 +31,17 @@ function checkInContentPreferences(win) 
 }
 
 function test() {
   waitForExplicitFinish();
 
   Services.prefs.setBoolPref("offline-apps.allow_by_default", false);
 
   // Open a new tab.
-  gBrowser.selectedTab = gBrowser.addTab(URL);
+  gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, URL);
   registerCleanupFunction(() => gBrowser.removeCurrentTab());
 
 
   Promise.all([
     // Wait for a notification that asks whether to allow offline storage.
     promiseNotification(),
     // Wait for the tab to load.
     BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser),

--- a/browser/base/content/test/general/browser_overflowScroll.js
+++ b/browser/base/content/test/general/browser_overflowScroll.js
@@ -1,41 +1,47 @@
 var tabstrip = gBrowser.tabContainer.mTabstrip;
 var scrollbox = tabstrip._scrollbox;
 var originalSmoothScroll = tabstrip.smoothScroll;
 var tabs = gBrowser.tabs;
 
 var rect = ele => ele.getBoundingClientRect();
 var width = ele => rect(ele).width;
+var height = ele => rect(ele).height;
 var left = ele => rect(ele).left;
 var right = ele => rect(ele).right;
 var isLeft = (ele, msg) => is(left(ele) + tabstrip._tabMarginLeft, left(scrollbox), msg);
 var isRight = (ele, msg) => is(right(ele) - tabstrip._tabMarginRight, right(scrollbox), msg);
 var elementFromPoint = x => tabstrip._elementFromPoint(x);
 var nextLeftElement = () => elementFromPoint(left(scrollbox) - 1);
 var nextRightElement = () => elementFromPoint(right(scrollbox) + 1);
 var firstScrollable = () => tabs[gBrowser._numPinnedTabs];
 
+var clickCenter = (ele, opts) => {
+  EventUtils.synthesizeMouse(ele, Math.ceil(width(ele) / 2),
+                             Math.ceil(height(ele) / 2), opts);
+}
+
 function test() {
   requestLongerTimeout(2);
   waitForExplicitFinish();
 
   // If the previous (or more) test finished with cleaning up the tabs,
   // there may be some pending animations. That can cause a failure of
   // this tests, so, we should test this in another stack.
   setTimeout(doTest, 0);
 }
 
 function doTest() {
   tabstrip.smoothScroll = false;
 
   var tabMinWidth = parseInt(getComputedStyle(gBrowser.selectedTab, null).minWidth);
   var tabCountForOverflow = Math.ceil(width(tabstrip) / tabMinWidth * 3);
   while (tabs.length < tabCountForOverflow)
-    gBrowser.addTab("about:blank", {skipAnimation: true});
+    BrowserTestUtils.addTab(gBrowser, "about:blank", {skipAnimation: true});
   gBrowser.pinTab(tabs[0]);
 
   tabstrip.addEventListener("overflow", runOverflowTests);
 }
 
 function runOverflowTests(aEvent) {
   if (aEvent.detail != 1 ||
       aEvent.target != tabstrip)
@@ -55,28 +61,28 @@ function runOverflowTests(aEvent) {
   EventUtils.synthesizeMouseAtCenter(downButton, {});
   isRight(element, "Scrolled one tab to the right with a single click");
 
   gBrowser.selectedTab = tabs[tabs.length - 1];
   ok(right(gBrowser.selectedTab) <= right(scrollbox), "Selecting the last tab scrolls it into view " +
      "(" + right(gBrowser.selectedTab) + " <= " + right(scrollbox) + ")");
 
   element = nextLeftElement();
-  EventUtils.synthesizeMouse(upButton, 1, 1, {});
+  clickCenter(upButton, {});
   isLeft(element, "Scrolled one tab to the left with a single click");
 
   let elementPoint = left(scrollbox) - width(scrollbox);
   element = elementFromPoint(elementPoint);
   if (elementPoint == right(element)) {
     element = element.nextSibling;
   }
-  EventUtils.synthesizeMouse(upButton, 1, 1, {clickCount: 2});
+  clickCenter(upButton, {clickCount: 2});
   isLeft(element, "Scrolled one page of tabs with a double click");
 
-  EventUtils.synthesizeMouse(upButton, 1, 1, {clickCount: 3});
+  clickCenter(upButton, {clickCount: 3});
   var firstScrollableLeft = left(firstScrollable());
   ok(left(scrollbox) <= firstScrollableLeft, "Scrolled to the start with a triple click " +
      "(" + left(scrollbox) + " <= " + firstScrollableLeft + ")");
 
   while (tabs.length > 1)
     gBrowser.removeTab(tabs[0]);
 
   tabstrip.smoothScroll = originalSmoothScroll;

--- a/browser/base/content/test/general/browser_pinnedTabs.js
+++ b/browser/base/content/test/general/browser_pinnedTabs.js
@@ -22,17 +22,17 @@ function PinUnpinHandler(tab, eventName)
   gBrowser.tabContainer.addEventListener(eventName, function(e) {
     if (e.originalTarget == tab) {
       self.eventCount++;
     }
   }, {capture: true, once: true});
 }
 
 function test() {
-  tabs = [gBrowser.selectedTab, gBrowser.addTab(), gBrowser.addTab(), gBrowser.addTab()];
+  tabs = [gBrowser.selectedTab, BrowserTestUtils.addTab(gBrowser), BrowserTestUtils.addTab(gBrowser), BrowserTestUtils.addTab(gBrowser)];
   indexTest(0, 0);
   indexTest(1, 1);
   indexTest(2, 2);
   indexTest(3, 3);
 
   var eh = new PinUnpinHandler(tabs[3], "TabPinned");
   gBrowser.pinTab(tabs[3]);
   is(eh.eventCount, 2, "TabPinned event should be fired");

--- a/browser/base/content/test/general/browser_relatedTabs.js
+++ b/browser/base/content/test/general/browser_relatedTabs.js
@@ -6,17 +6,17 @@ add_task(async function() {
   is(gBrowser.tabs.length, 1, "one tab is open initially");
 
   // Add several new tabs in sequence, interrupted by selecting a
   // different tab, moving a tab around and closing a tab,
   // returning a list of opened tabs for verifying the expected order.
   // The new tab behaviour is documented in bug 465673
   let tabs = [];
   function addTab(aURL, aReferrer) {
-    let tab = gBrowser.addTab(aURL, {referrerURI: aReferrer});
+    let tab = BrowserTestUtils.addTab(gBrowser, aURL, {referrerURI: aReferrer});
     tabs.push(tab);
     return BrowserTestUtils.browserLoaded(tab.linkedBrowser);
   }
 
   await addTab("http://mochi.test:8888/#0");
   gBrowser.selectedTab = tabs[0];
   await addTab("http://mochi.test:8888/#1");
   await addTab("http://mochi.test:8888/#2", gBrowser.currentURI);

--- a/browser/base/content/test/general/browser_removeTabsToTheEnd.js
+++ b/browser/base/content/test/general/browser_removeTabsToTheEnd.js
@@ -1,17 +1,17 @@
 /* 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/. */
 
 function test() {
   // Add two new tabs after the original tab. Pin the first one.
   let originalTab = gBrowser.selectedTab;
-  let newTab1 = gBrowser.addTab();
-  gBrowser.addTab();
+  let newTab1 = BrowserTestUtils.addTab(gBrowser);
+  BrowserTestUtils.addTab(gBrowser);
   gBrowser.pinTab(newTab1);
 
   // Check that there is only one closable tab from originalTab to the end
   is(gBrowser.getTabsToTheEndFrom(originalTab).length, 1,
     "One unpinned tab to the right");
 
   // Remove tabs to the end
   gBrowser.removeTabsToTheEndFrom(originalTab);

--- a/browser/base/content/test/general/browser_restore_isAppTab.js
+++ b/browser/base/content/test/general/browser_restore_isAppTab.js
@@ -97,17 +97,17 @@ var restart = async function(browser) {
 
   let tab = gBrowser.getTabForBrowser(browser);
   SessionStore.reviveCrashedTab(tab);
 
   await promiseTabLoaded(tab);
 };
 
 add_task(async function navigate() {
-  let tab = gBrowser.addTab("about:robots");
+  let tab = BrowserTestUtils.addTab(gBrowser, "about:robots");
   let browser = tab.linkedBrowser;
   gBrowser.selectedTab = tab;
   await waitForDocLoadComplete();
   loadFrameScript(browser);
   let isAppTab = await isBrowserAppTab(browser);
   ok(!isAppTab, "Docshell shouldn't think it is an app tab");
 
   gBrowser.pinTab(tab);
@@ -136,17 +136,17 @@ add_task(async function navigate() {
 
   gBrowser.removeCurrentTab();
 });
 
 add_task(async function crash() {
   if (!gMultiProcessBrowser || !("nsICrashReporter" in Ci))
     return;
 
-  let tab = gBrowser.addTab(DUMMY);
+  let tab = BrowserTestUtils.addTab(gBrowser, DUMMY);
   let browser = tab.linkedBrowser;
   gBrowser.selectedTab = tab;
   await waitForDocLoadComplete();
   loadFrameScript(browser);
   let isAppTab = await isBrowserAppTab(browser);
   ok(!isAppTab, "Docshell shouldn't think it is an app tab");
 
   gBrowser.pinTab(tab);

--- a/browser/base/content/test/general/browser_save_video_frame.js
+++ b/browser/base/content/test/general/browser_save_video_frame.js
@@ -93,17 +93,17 @@ add_task(async function() {
 
   // Make sure that we clean these things up when we're done.
   registerCleanupFunction(function() {
     mockTransferRegisterer.unregister();
     MockFilePicker.cleanup();
     destDir.remove(true);
   });
 
-  let tab = gBrowser.addTab();
+  let tab = BrowserTestUtils.addTab(gBrowser);
   gBrowser.selectedTab = tab;
   let browser = tab.linkedBrowser;
   info("Loading video tab");
   await promiseTabLoadEvent(tab, VIDEO_URL);
   info("Video tab loaded.");
 
   let context = document.getElementById("contentAreaContextMenu");
   let popupPromise = promisePopupShown(context);

--- a/browser/base/content/test/general/browser_selectTabAtIndex.js
+++ b/browser/base/content/test/general/browser_selectTabAtIndex.js
@@ -11,17 +11,17 @@ function test() {
   function sendAccelKey(key) {
     // Make sure the keystroke goes to chrome.
     document.activeElement.blur();
     EventUtils.synthesizeKey(key.toString(), { altKey: isLinux, accelKey: !isLinux });
   }
 
   function createTabs(count) {
     for (let n = 0; n < count; n++)
-      gBrowser.addTab();
+      BrowserTestUtils.addTab(gBrowser);
   }
 
   function testKey(key, expectedTab) {
     sendAccelKey(key);
     assertTab(expectedTab);
   }
 
   function testIndex(index, expectedTab) {

--- a/browser/base/content/test/general/browser_star_hsts.js
+++ b/browser/base/content/test/general/browser_star_hsts.js
@@ -11,17 +11,17 @@ add_task(async function test_star_redire
     let sss = Cc["@mozilla.org/ssservice;1"]
                 .getService(Ci.nsISiteSecurityService);
     sss.removeState(Ci.nsISiteSecurityService.HEADER_HSTS,
                     NetUtil.newURI("http://example.com/"), 0);
     PlacesUtils.bookmarks.removeFolderChildren(PlacesUtils.unfiledBookmarksFolderId);
     gBrowser.removeCurrentTab();
   });
 
-  let tab = gBrowser.selectedTab = gBrowser.addTab();
+  let tab = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser);
   // This will add the page to the HSTS cache.
   await promiseTabLoadEvent(tab, secureURL, secureURL);
   // This should transparently be redirected to the secure page.
   await promiseTabLoadEvent(tab, unsecureURL, secureURL);
 
   await promiseStarState(BookmarkingUI.STATUS_UNSTARRED);
 
   let promiseBookmark = promiseOnBookmarkItemAdded(gBrowser.currentURI);

--- a/browser/base/content/test/general/browser_subframe_favicons_not_used.js
+++ b/browser/base/content/test/general/browser_subframe_favicons_not_used.js
@@ -1,16 +1,16 @@
 /* Make sure <link rel="..."> isn't respected in sub-frames. */
 
 function test() {
   waitForExplicitFinish();
 
   let testPath = getRootDirectory(gTestPath);
 
-  let tab = gBrowser.addTab(testPath + "file_bug970276_popup1.html");
+  let tab = BrowserTestUtils.addTab(gBrowser, testPath + "file_bug970276_popup1.html");
 
   tab.linkedBrowser.addEventListener("load", function() {
     let expectedIcon = testPath + "file_bug970276_favicon1.ico";
     is(gBrowser.getIcon(tab), expectedIcon, "Correct icon.");
 
     gBrowser.removeTab(tab);
 
     finish();

--- a/browser/base/content/test/general/browser_tabReorder.js
+++ b/browser/base/content/test/general/browser_tabReorder.js
@@ -1,17 +1,17 @@
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/ */
 
 add_task(async function() {
   let initialTabsLength = gBrowser.tabs.length;
 
-  let newTab1 = gBrowser.selectedTab = gBrowser.addTab("about:robots", {skipAnimation: true});
-  let newTab2 = gBrowser.selectedTab = gBrowser.addTab("about:about", {skipAnimation: true});
-  let newTab3 = gBrowser.selectedTab = gBrowser.addTab("about:config", {skipAnimation: true});
+  let newTab1 = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "about:robots", {skipAnimation: true});
+  let newTab2 = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "about:about", {skipAnimation: true});
+  let newTab3 = gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "about:config", {skipAnimation: true});
   registerCleanupFunction(function() {
     while (gBrowser.tabs.length > initialTabsLength) {
       gBrowser.removeTab(gBrowser.tabs[initialTabsLength]);
     }
   });
 
   is(gBrowser.tabs.length, initialTabsLength + 3, "new tabs are opened");
   is(gBrowser.tabs[initialTabsLength], newTab1, "newTab1 position is correct");