Remove role="form" on a form element.

Role Form should be use on a region of the document that  represents a collection of form-associated elements.
<div role=”form”></div> GOOD
<form role=”form”></form> BAD

templates/default/login.html

@@ -16,7 +16,7 @@
         <article class="col-main" role="main" aria-labelledby="main-label">
             <h1 id="main-label" class="page-header">{intl l="Login"}</h1>
             {form name="thelia.front.customer.login"}
-            <form id="form-login" action="{url path="/login"}" method="post" role="form" {form_enctype form=$form} novalidate>
+            <form id="form-login" action="{url path="/login"}" method="post" {form_enctype form=$form} novalidate>
                 {if $form_error}<div class="alert alert-danger">{$form_error_message}</div>{/if}
                 {form_field form=$form field='success_url'}
                     <input type="hidden" name="{$name}" value="{navigate to="return_to"}"> {* the url the user is redirected to on login success *}