Support for adding item classes on the nesting element

[ndm2]

Consider adding support for setting item classes like ancestorClass on the nesting element, currently only the link/text elements can inherit/consume item classes.

<ul>
    <li class="active-ancestor has-dropdown">
        <a href="#">Services</a>
        <ul class="active-ancestor dropdown"> <!-- < nesting element -->
            <li class='active'>
                <a href="/pages/display/research">Research</a>
            </li>
        </ul>
    </li>
</ul>

• Does it make sense from a semantic point of view?
• Can it be integrated into the current inherit/consume support?

/cc @challgren