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chromium/third_party/blink/web_tests/fast/forms/file/disabling-file-busy-loop.html 

<!DOCTYPE html>
<html>
<head>
<style>
.foo[disabled] {}
</style>
</head>
<body>
<input type="file" id="fileUpload">
<div id=console></div>
<script>
if (window.testRunner)
    testRunner.dumpAsText();
document.getElementById('fileUpload').disabled = true;
document.getElementById('console').innerText = 'PASS if this text is visible.';
</script>
</body>
</html>