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chromium/third_party/blink/web_tests/media/webkit-media-controls-display.html 

<!DOCTYPE html>
<p>Overloading ::-webkit-media-controls display property. PASS if it doesn't crash.</p>
<script>
var displayValues = ["-webkit-flex",
    "-webkit-inline-flex", "block", "flex", "grid", "inline", "inline-block",
    "inline-flex", "inline-grid", "inline-table", "list-item", "none", "table",
    "table-caption", "table-cell", "table-column", "table-column-group",
    "table-footer-group", "table-header-group", "table-row", "table-row-group"];

var styleSheet = "video { width: 200px; height: 30px; }\n";

displayValues.forEach(function(value, idx) {
    var video = document.createElement("video");
    video.controls = true;
    video.id = "video" + idx;
    document.body.appendChild(video);

    styleSheet += "#video" + idx + "::-webkit-media-controls { display: " + value + " !important; }\n";
});

var style = document.createElement("style");
style.textContent = styleSheet;
document.head.appendChild(style);
</script>