is (cssSelector) { // eslint-disable-line no-unused-vars
    /* istanbul ignore next */
    throw new Error(NOT_IMPLEMENTED)
  }
Checks if a given CSS selector matches for this element.
*Attention**
    This method is currently not implemented for {VirtualElement}.
    This means you should use it only in importer implementations.

    @param {String} cssSelector
    @returns {Boolean}