handleNCG method from es.regexp.constructor does not work correctly in some cases.

If named captured group placed inside non-capturing group(or other group, that doesn't follow (?<group_name>...) pattern) then group id counter extra incremented.

 case chr === '(':
        if (exec(IS_NCG, stringSlice(string, index + 1))) {
          index += 2;
          ncg = true;
          // where increment is needed
        }
        result += chr;
        groupid++;  // where actually incremented
        continue;

Real example: H_REGEX from vscode repository.
const H_REGEX = /(?<tag>[\w\-]+)?(?:#(?<id>[\w\-]+))?(?<class>(?:\.(?:[\w\-]+))*)(?:@(?<name>(?:[\w\_])+))?/;

When it used through RegExp constructor new RegExp('(?<tag>[\\w\\-]+)?(?:#(?<id>[\\w\\-]+))?(?<class>(?:\\.(?:[\\w\\-]+))*)(?:@(?<name>(?:[\\w\\_])+))?'), exec method return wrong groups values. Tested on 'div.editor.original@original' input value.
With polyfill:

{
    "tag": "div",
    "id": ".editor.original",
    "name": undefined,
    "class": "original"
}

Native:

{
    "tag": "div",
    "id": undefined,
    "class": ".editor.original",
    "name": "original"
}

Link to test