B2G/gecko/browser/devtools/styleinspector/CssLogic.jsm
/**
   * Retrieve the number of rules in this stylesheet.
   *
   * @return {number} the number of nsIDOMCSSRule objects in this stylesheet.
   */
Retrieve the number of rules in this stylesheet.
@return {number} the number of nsIDOMCSSRule objects in this stylesheet.
Retrieve the number of rules in this stylesheet . @return { number } the number of nsIDOMCSSRule objects in this stylesheet .
get ruleCount()
  {
    return this._ruleCount > -1 ?
        this._ruleCount :
        this.domSheet.cssRules.length;
  }
get ruleCount ( ) { return this . _ruleCount > - 1 ? this . _ruleCount : this . domSheet . cssRules . length ; }
Retrieve the number of rules in this stylesheet.
Retrieve the number of rules in this stylesheet .