Fixed #16335 -- Clarified an unintuitive behavior.

    * Method call

    * List-index lookup

    This can cause some unexpected behavior with objects that override

    dictionary lookup. For example, consider the following code snippet that

    attempts to loop over a ``collections.defaultdict``::

        {% for k, v in defaultdict.iteritems %}

	    Do something with k and v here...

        {% endfor %}

    Because dictionary lookup happens first, that behavior kicks in and provides

    a default value instead of using the intended ``.iteritems()``

    method. In this case, consider converting to a dictionary first.

In the above example, ``{{ section.title }}`` will be replaced with the

``title`` attribute of the ``section`` object.