This hopefully fixes this flaky error in test_notifications_with_ask__true on
OS X:
Failed: Logged unexpected errors:
LogLine('22:40:06 DEBUG js webpage:javaScriptConsoleMessage:531 [http://localhost:57758/data/prompt/notifications.html:28] [FAIL] unknown initial value for Notification.permission: denied')
[...]
testprocess.WaitForTimeout: Timed out after 15000ms waiting for {'message': 'Entering mode KeyMode.* (reason: question asked)'}.