chromium/third_party/blink/web_tests/http/tests/xmlhttprequest/request-encoding3.html

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<body>
<p>Test for <a href="http://crbug.com/277526">http://crbug.com/277526</a>:
XMLHttpRequest normalizes the data sent to the server into Unicode NFC.</p>
<div id="result">FAIL: script didn't run to completion.</div>
<script>

    if (window.testRunner)
        testRunner.dumpAsText();

    var xhr = new XMLHttpRequest;
    xhr.open("POST", "resources/post-echo-as-utf-8.cgi", false);
    xhr.setRequestHeader("content-type", "application/json; charset=UTF-8");
    xhr.send("{\"key\":\"\\n\u0300\"}");
    if (xhr.responseText == "{\"key\":\"\\n\u0300\"}")
        document.getElementById("result").firstChild.data = "SUCCESS";
    else
        document.getElementById("result").firstChild.data = "FAILURE: '" + xhr.responseText + "'";

</script>
</body>
</html>