Use the 'toctree-wrapper' class for the sphinx13 theme (#11129)

Author: mgeier

doc/_templates/contents.html

@@ -2,5 +2,7 @@
 {% set title = _('Sphinx documentation contents') %}
 {% block body %}
 <h1>{{ _('Sphinx documentation contents') }}</h1>
+<div class="toctree-wrapper compound">
 {{ toctree(includehidden=True, collapse=False, maxdepth=3) }}
+</div>
 {% endblock %}