LayoutTests/fast/css/create-columns-onload-crash.html

<script>
    if (window.testRunner)
        testRunner.dumpAsText();
  onload = () => {
    let cssStyleValue = CSSMathValue.parseAll('columns', 'auto')[0];
    document.body.attributeStyleMap.append('grid-auto-columns', cssStyleValue);
  };
</script>
<div>This test should not crash</div>