ling scope so it has an api
      // similar to that of an element wrt style properties
      get _styleProperties() {
        if (!this._properties) {
          // force rules to reparse since they may be out of date
          styleProperties.decorateStyles(this._styles);
          // NOTE: reset cache for own properties; it may have been set when
          // an element in an import applied styles (e.g. custom-style)
          this._styles._scopeStyleProperties = null;
          this._properties = stylePr