code: function(el, document) {
              var self    = this;
  
              self.callActions('beforeCacheDom', arguments);
  
              self.dom.document  = document;
              self.dom.body      = self.dom.document.querySelector('body');
              self.dom.container = el;
              self.dom.parent    = el;
  
              self.callActions('afterCacheDom', arguments);
          }
docs: Caches references of DOM elements neccessary for the mixer's functionality.
  
  @private
  @instance
  @since   3.0.0
  @param   {HTMLElement}       el
  @param   {HTMLHtmlElement}   document
  @return  {void}