<style>
  *::first-letter {
    -webkit-initial-letter: 2;
  }
  * {
    bottom: 0vh;
    writing-mode: vertical-lr;
  }
</style>
<script>
  if (window.testRunner)
      testRunner.dumpAsText();
  console.log("This test passes if it does not crash.");
  document.styleSheets[0].insertRule(`*::before { content: 'ab' url(); }`);
</script>