estharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/common/PrefixedPostMessage.js"></script>
<script>
var featuresPrefix = `top=0,left=0,width=401,`;
var windowURL = 'resources/message-opener.html';

// https://html.spec.whatwg.org/multipage/infrastructure.html#rules-for-parsing-integers

setup (() => {
  // Before running tests, open a window using features that mimic
  // what would happen if the feature tested here were set to 0
  // for comparison later.
  var 