diff --git a/browser/base/content/tabbrowser.xml b/browser/base/content/tabbrowser.xml
index c093fb410787..9b2116218463 100644
--- a/browser/base/content/tabbrowser.xml
+++ b/browser/base/content/tabbrowser.xml
@@ -1957,8 +1957,8 @@
                 aTab._pendingPermitUnload = true;
                 let permitUnload = ds.contentViewer.permitUnload();
                 delete aTab._pendingPermitUnload;
-                // If we were closed during the unload, we return false now so
-                // we don't (try to) close the same tab again. Of course, we
+                // If we were closed during onbeforeunload, we return false now
+                // so we don't (try to) close the same tab again. Of course, we
                 // also stop if the unload was cancelled by the user:
                 if (aTab.closing || !permitUnload) {
                   // NB: deliberately keep the _closedDuringPermitUnload set to
diff --git a/browser/base/content/test/general/browser_double_close_tab.js b/browser/base/content/test/general/browser_double_close_tab.js
index 2e1d5f70659f..2dbe0f83228c 100644
--- a/browser/base/content/test/general/browser_double_close_tab.js
+++ b/browser/base/content/test/general/browser_double_close_tab.js
@@ -1,4 +1,4 @@
-"use strict"
+"use strict";
 const TEST_PAGE = "http://mochi.test:8888/browser/browser/base/content/test/general/file_double_close_tab.html";
 let testTab;
 
@@ -43,9 +43,9 @@ add_task(function*() {
   // everything gets messed up and the promise's .then callbacks never get
   // called, despite resolve() being called just fine.
   let dialogNode = yield new Promise(resolveOuter => {
-    waitForDialog(function(dialogNode) {
+    waitForDialog(dialogNode => {
       waitForDialogDestroyed(dialogNode, () => {
-        let doCompletion = () => setTimeout(resolveOuter, 10);
+        let doCompletion = () => setTimeout(resolveOuter, 0);
         info("Now checking if dialog is destroyed");
         ok(!dialogNode.parentNode, "onbeforeunload dialog should be gone.");
         if (dialogNode.parentNode) {