Firefox tabindex not following source order

Question

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>