chromium/third_party/blink/web_tests/typedcssom/the-stylepropertymap/declared/delete-rule-crash.html

<!DOCTYPE html>
<html>
<head>
<title>Crash test for using declared style map with no associated style rule</title>
<style>
#target { color: red; }
</style>
</head>
<body>
<script src="../../../resources/testharness.js"></script>
<script src="../../../resources/testharnessreport.js"></script>
<script>
test(() => {
  var sheet = document.styleSheets[0];
  var styleMap = sheet.cssRules[0].styleMap;
  sheet.deleteRule(0);
  gc();

  // Make sure none of the styleMap methods crash.
  styleMap.get('color');
  styleMap.getAll('color');
  [...styleMap];
  styleMap.append('transition-duration', '1s');
  styleMap.delete('color');
  styleMap.set('width', '10px');
  styleMap.clear();
  styleMap.size;
}, "Deleting a style rule does not crash the corresponding declared style map");
</script>