fix validation disabling attribute

templates/web/complete_challenge.tt2.html

@@ -24,7 +24,7 @@
     </div>
 
     <div class="actions clearfix">
-        <button type="submit" class="button" name="action" value="select_email" novalidate>[% lh.maketext("Previous") %]</button>
+        <button type="submit" class="button" name="action" value="select_email" formnovalidate>[% lh.maketext("Previous") %]</button>
         <button type="submit" class="button" name="action" value="create_accounts">[% lh.maketext("Next") %]</button>
     </div>
 </form>

templates/web/select_sp.tt2.html

@@ -29,7 +29,7 @@
     </div>
 
     <div class="actions clearfix">
-        <button type="submit" class="button" name="action" value="select_federation" novalidate>[% lh.maketext("Previous") %]</button>
+        <button type="submit" class="button" name="action" value="select_federation" formnovalidate>[% lh.maketext("Previous") %]</button>
         <button type="submit" class="button" name="action" value="select_email">[% lh.maketext("Next") %]</button>
     </div>
 </form>