Bug 1402555 - followup to close the urlbar popup, since some tests are unhappy with the status quo. r=post-facto

MozReview-Commit-ID: It8GhKfWj3n

--HG--
extra : rebase_source : 5c1218eac9eaa04aa75b7640513867c938ca0d2b

browser/base/content/test/urlbar/browser_urlbar_remove_match.js

@@ -25,4 +25,7 @@ add_task(async function test_remove_history() {
   await BrowserTestUtils.waitForCondition(
     () => !gURLBar.popup.richlistbox.children.some(c => !c.collapsed && c.getAttribute("ac-value") == TEST_URL),
     "Waiting for the result to disappear");
+
+  gURLBar.popup.hidePopup();
+  await promisePopupHidden(gURLBar.popup);
 });