title: Twig impossible to invoke a method on a string variable
body: <p>After updating <code>"twig/twig"</code> to <code>"v2.4.4"</code> I have an error when calling macro function.</p>
  
  <pre><code>Impossible to invoke a method ("widget_prototype") on a string variable (":ERP/timesheets:_form_part.html.twig").
  </code></pre>
  
  <p>My macro:</p>
  
  <pre><code>{% macro widget_prototype(widget, remove_text) %}
  {% if widget.vars.prototype is defined %}
      {% set form = widget.vars.prototype %}
      {% set name = widget.vars.prototype.vars.name %}
  {% else %}
      {% set form = widget %}
      {% set name = widget.vars.full_name %}
  {% endif %}
  </code></pre>
  
  <p>Calling macro part:</p>
  
  <pre><code>{% include ':ERP/timesheets:_data_content_supply_from_widget.html.twig' with {form:form, name:name} %}
  
  {% endmacro %}
  
              &lt;div id="post_supplies"
               data-prototype="{{ _self.widget_prototype(form.supplies, 'remove'|trans({}, 'common'))|escape }}"
               style="margin-bottom: 5px"&gt;
              {% for widget in form.supplies.children %}
                  {{ _self.widget_prototype(widget, 'remove'|trans({}, 'common')) }}
              {% endfor %}
          &lt;/div&gt;
  </code></pre>
  
  <p>How to correctly call macro? Tried calling without <code>_self</code> and I have the error: <code>Unknown "widget_prototype" function.</code> </p>