B2G/gecko/browser/devtools/styleinspector/CssLogic.jsm
/**
   * Get the number nsIDOMCSSRule objects in the document, counted from all of
   * the stylesheets. System sheets are excluded. If a filter is active, this
   * tells only the number of nsIDOMCSSRule objects inside the selected
   * CSSStyleSheet.
   *
   * WARNING: This only provides an estimate of the rule count, and the results
   * could change at a later date. Todo remove this
   *
   * @return {number} the number of nsIDOMCSSRule (all rules).
   */
Get the number nsIDOMCSSRule objects in the document, counted from all of
the stylesheets. System sheets are excluded. If a filter is active, this
tells only the number of nsIDOMCSSRule objects inside the selected
CSSStyleSheet.

This only provides an estimate of the rule count, and the results
could change at a later date. Todo remove this

@return {number} the number of nsIDOMCSSRule (all rules).
Get the number nsIDOMCSSRule objects in the document counted from all of the stylesheets . System sheets are excluded . If a filter is active this tells only the number of nsIDOMCSSRule objects inside the selected CSSStyleSheet . This only provides an estimate of the rule count and the results could change at a later date . Todo remove this @return { number } the number of nsIDOMCSSRule ( all rules ) .
get ruleCount()
  {
    if (!this._sheetsCached) {
      this._cacheSheets();
    }
    return this._ruleCount;
  }
get ruleCount ( ) { if ( ! this . _sheetsCached ) { this . _cacheSheets ( ) ; } return this . _ruleCount ; }
Get the number nsIDOMCSSRule objects in the document, counted from all of
 the stylesheets.
Get the number nsIDOMCSSRule objects in the document counted from all of the stylesheets .