Firefox tabindex not following source order

问题:

Tabbing on Chrome follows the source order for this form nicely, whereas Firefox skips the password reset link, and goes straight to the next thing after the form, which is a button. Does Firefox prioritise buttons and form elements over links for tabindexing? It doesn't make any difference what tabindex number I put on the link

<form method="POST" action="/login" accept-charset="UTF-8">

    <label><span class="element-invisible">Email address</span>
        <input placeholder="Email address" name="login_email" type="email"> 
    </label>
    <label><span class="element-invisible">Password</span>
        <input placeholder="Password" name="login_password" value="" type="password">
    </label>
        <input class="buttonNoStyle submitButtonSolid" value="Login" type="submit">

    <div class="underForm">
        <input id="rememberMe" name="remember" class="element-invisible" value="all" checked="" type="checkbox">
        <label class="rememberMe" for="rememberMe">
            Remember me
        </label>

        <div class="forgot">|&nbsp;&nbsp; <a tabindex="1" class="forgotLink" href="/password/reset">Forgotten password</a></div>

    </div><!-- /underForm -->

</form>
<button type="button" class="buttonNoStyle standardButton thinnerButton whiteButton" id="logIn2">Log in</button>