Bug 1665820, r=emalysz

Differential Revision: https://phabricator.services.mozilla.com/D92589
mozilla · Oct 14, 2020 · 5a9ad19 · 5a9ad19
1 parent 16aaee1
commit 5a9ad19
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/browser/extensions/screenshots/selector/ui.js b/browser/extensions/screenshots/selector/ui.js
@@ -365,6 +365,7 @@ this.ui = (function() { // eslint-disable-line no-unused-vars
           this.element.setAttribute("role", "dialog");
           this.element.onload = watchFunction(() => {
             msgsPromise.then(([cancelTitle, copyTitle, downloadTitle]) => {
+              assertIsBlankDocument(this.element.contentDocument);
               this.document = this.element.contentDocument;
               this.window = this.element.contentWindow;
               // eslint-disable-next-line no-unsanitized/property