function onRuleParsed(rule)
        {
            if (!rule)
                return Promise.resolve(/** @type {?WebInspector.CSSRule} */(null));

            return this._computeMatchingSelectors(node.id, rule.selectors)
                .then(updateMatchingSelectors.bind(null, rule));
        }
@param {?WebInspector.CSSRule} rule
@return {!Promise<?WebInspector.CSSRule>}
@this {WebInspector.CSSStyleModel}