Bug 1253134 - Sorry eslint, I am so sorry. r=me

browser/components/extensions/test/browser/browser_ext_windows_update.js

@@ -127,7 +127,6 @@ add_task(function* testWindowUpdate() {
 });
 
 add_task(function* () {
-  let window1 = window;
   let window2 = yield BrowserTestUtils.openNewBrowserWindow();
 
   let extension = ExtensionTestUtils.loadExtension({