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chromium/third_party/blink/web_tests/fast/dom/Window/resources/open-sibling-subframe.html 

<script>
function test()
{
    open("sibling-subframe-content.html", "sibling");
}
</script>
<body onload="test()">
This frame will try to replace the contents of the frame to the right.
If the bug still occurs, pop-up blocking will prevent it from doing so.
</body>