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chromium/third_party/blink/web_tests/fast/css-generated-content/visibleContentHiddenParent.html 

<html>
<head>
<style>
    .linkAddComment {visibility:hidden;} 
    .linkAddComment:before {content:"This test passes if it does not crash, and this text appears."; visibility:visible;}
</style>
</head>
<body>
<a class="linkAddComment">But it fails if this text appears.</a>
</body>
</html>