表单 – 浏览器如何确定哪些表单字段是用户名/密码？

背景：

我有一个注册页面,其中包含以下表格：

<form action="/BlaBla/Account/Register" method="post">
    <div>
        <fieldset>
            <legend>Account Information</legend>
            <p>
                <label for="username">
                    Username:</label>
                <input id="username" name="username" type="text" value="" />
            </p>
            <p>
                <label for="email">
                    Email:</label>
                <input id="email" name="email" type="text" value="" />
            </p>
            <p>
                <label for="invitationCode">
                    Invitation Code:</label>
                <input id="invitationCode" name="invitationCode" type="text" value="" />
            </p>
            <p>
                <label for="securityQuestion">
                    Security question:</label>
                <input id="securityQuestion" name="securityQuestion" type="text" value="" />
            </p>
            <p>
                <label for="securityAnswer">
                    Security answer:</label>
                <input id="securityAnswer" name="securityAnswer" type="text" value="" />
            </p>
            <p>
                <label for="password">
                    Password:</label>
                <input id="password" name="password" type="password" />
            </p>
            <p>
                <label for="confirmPassword">
                    Confirm password:</label>
                <input id="confirmPassword" name="confirmPassword" type="password" />
            </p>
            <p class="buttons">
                <input type="submit" value="Register" />
            </p>
        </fieldset>
    </div>
    </form>

Mozilla似乎认为字段securityAnswer和密码是用户/ pw字段,带来尴尬的后果(安全答案存储为用户名是坏的).