# HG changeset patch
# User Kaizer Soze <kaizersoze915@gmail.com>
# Date 1602665311 0
#      Wed Oct 14 08:48:31 2020 +0000
# Node ID 5a4b06d86f52685f2a4b51538f9ac3a7d9be265b
# Parent  1547b1a7189503e22eaa2180fa9597a044b91ff8
Bug 1665820, r=emalysz

Differential Revision: https://phabricator.services.mozilla.com/D92589

diff -r 1547b1a71895 -r 5a4b06d86f52 browser/extensions/screenshots/selector/ui.js
--- a/browser/extensions/screenshots/selector/ui.js	Wed Oct 14 09:17:27 2020 +0000
+++ b/browser/extensions/screenshots/selector/ui.js	Wed Oct 14 08:48:31 2020 +0000
@@ -361,6 +361,7 @@
           this.element.setAttribute("role", "dialog");
           this.element.onload = watchFunction(() => {
             msgsPromise.then(([cancelTitle, copyTitle, downloadTitle]) => {
+              assertIsBlankDocument(this.element.contentDocument);
               this.document = this.element.contentDocument;
               // eslint-disable-next-line no-unsanitized/property
               this.document.documentElement.innerHTML = `