code: function nodeCollector_queryAnonymousNodes(aAttribute, aValue) {
      var node = this._document.getAnonymousElementByAttribute(this._root,
                                                               aAttribute,
                                                               aValue);
      this.nodes = node ? [node] : [ ];
  
      return this;
    }
docs: Find anonymouse nodes with the specified attribute and value
  
  @param {string} aAttribute
  DOM attribute of the wanted node
  @param {string} aValue
  Value of the DOM attribute
  
  @returns The class instance
  @type {object}