--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -5171,17 +5171,17 @@ var XULBrowserWindow = {
     delete this._elementsForViewSource;
     return (this._elementsForViewSource = [
       document.getElementById("context-viewsource"),
       document.getElementById("View:PageSource"),
     ]);
   },
 
   forceInitialBrowserNonRemote(aOpener) {
-    gBrowser.updateBrowserRemoteness(gBrowser.initialBrowser, {
+    gBrowser.updateBrowserRemoteness(gBrowser.selectedBrowser, {
       opener: aOpener,
       remoteType: E10SUtils.NOT_REMOTE,
     });
   },
 
   setDefaultStatus(status) {
     this.defaultStatus = status;
     StatusPanel.update();

--- a/browser/base/content/tabbrowser.js
+++ b/browser/base/content/tabbrowser.js
@@ -409,20 +409,16 @@
       this._tabForBrowser.set(browser, tab);
 
       this._appendStatusPanel();
 
       // This is the initial browser, so it's usually active; the default is false
       // so we have to update it:
       browser.docShellIsActive = this.shouldActivateDocShell(browser);
 
-      // Only necessary because of pageloader talos tests which access this.
-      // Bug 1508171 covers removing this.
-      this.initialBrowser = browser;
-
       let autoScrollPopup = browser._createAutoScrollPopup();
       autoScrollPopup.id = "autoscroller";
       document.getElementById("mainPopupSet").appendChild(autoScrollPopup);
       browser.setAttribute("autoscrollpopup", autoScrollPopup.id);
       this._autoScrollPopup = autoScrollPopup;
 
       // Hook the browser up with a progress listener.
       let tabListener = new TabProgressListener(tab, browser, true, false);

--- a/testing/talos/talos/pageloader/chrome/pageloader.js
+++ b/testing/talos/talos/pageloader/chrome/pageloader.js
@@ -231,21 +231,21 @@ function plInit() {
         // to this reinitialization on the switch.
         let remoteType = E10SUtils.getRemoteTypeForURI(
           pageUrls[0],
           /* remote */ true,
           /* fission */ Services.prefs.getBoolPref("fission.autostart")
         );
         let tabbrowser = browserWindow.gBrowser;
         if (remoteType) {
-          tabbrowser.updateBrowserRemoteness(tabbrowser.initialBrowser, {
+          tabbrowser.updateBrowserRemoteness(tabbrowser.selectedBrowser, {
             remoteType,
           });
         } else {
-          tabbrowser.updateBrowserRemoteness(tabbrowser.initialBrowser, {
+          tabbrowser.updateBrowserRemoteness(tabbrowser.selectedBrowser, {
             remoteType: E10SUtils.NOT_REMOTE,
           });
         }
 
         browserWindow.resizeTo(winWidth, winHeight);
         browserWindow.moveTo(0, 0);
         browserWindow.focus();
         content = browserWindow.gBrowser;