 var fd = new FormData(document.getElementById("form"));
        fd.append('key', undefined);
        fd.append('key', 'value1');
        assert_equals(fd.get('key'), "undefined");
    }, 'testFormDataAppendToFormUndefined2');
    test(function() {
        var fd = new FormData(document.getElementById("form"));
        fd.append('key', null);
        assert_equals(fd.get('key'), "null");
    }, 'testFormDataAppendToFormNull1');
    test(function() {
        var fd = new FormData(document.getElementById("for