Function getNativeFlags

docs/tests/v2/es6/js/sanddance.js:139212–139218

* Returns native `RegExp` flags used by a regex object. * * @private * @param {RegExp} regex Regex to check. * @returns {String} Native flags in use.

(regex)

 * @returns {String} Native flags in use.
 */
function getNativeFlags(regex) {
    return hasFlagsProp ? regex.flags :
    // Explicitly using `RegExp.prototype.toString` (rather than e.g. `String` or concatenation
    // with an empty string) allows this to continue working predictably when
    // `XRegExp.proptotype.toString` is overridden
    nativ.exec.call(/\/([a-z]*)$/i, RegExp.prototype.toString.call(regex))[1];
}

/**
 * Determines whether a regex has extended instance data used to track capture names.