<html>
<head>
    <style>
        div { border:1px solid red; }
        blockquote { border:1px solid blue; }
    </style>
    <script>
        function runTest() {
            if (window.testRunner)
                window.testRunner.dumpAsText();
        
            var blankLine = document.getElementById('blankLine');
            var s = window.getSelection();
            s.setPosition(blankLine, 0);
            document.execCommand("InsertNewlineInQuotedContent");
            
            if (blankLine.nextSibling.nodeName == "BR")
                console.log("SUCCESS! newline inserted AFTER quoted content");
            else
                console.log("FAILED! newline inserted BEFORE quoted content");
        }
    </script>
</head>
<body onload="runTest()">
    <div><br></div>
    <div contentEditable="true">
        <blockquote type="cite">Line of text</blockquote>
        <blockquote type="cite" id="blankLine"><br></blockquote>
    </div>
</body>
</html>