cssstyledeclaration-mutationrecord-004.html

<!doctype html>
<meta charset="utf-8">
<title>CSSOM: CSSStyleDeclaration.removeProperty doesn't queue a mutation record when not actually removed</title>
<link rel="help" href="https://drafts.csswg.org/cssom/#dom-cssstyledeclaration-setpropertyvalue">
<link rel="author" title="Emilio Cobos Álvarez" href="mailto:[email protected]">
<script src=/resources/testharness.js></script>
<script src=/resources/testharnessreport.js></script>
<script>
  let test = async_test("CSSStyleDeclaration.removeProperty doesn't queue a mutation record when not actually removed");
  document.documentElement.style.top = "0";
  let m = new MutationObserver(test.unreached_func("shouldn't queue a mutation record"));
  m.observe(document.documentElement,  { attributes: true });

  document.documentElement.style.removeProperty("width");
  requestAnimationFrame(() => test.done());
</script>

chromium/third_party/blink/web_tests/external/wpt/css/cssom/cssstyledeclaration-mutationrecord-004.html