[PHP 7.4] Add array spread operator

[TomasVotruba]

• php-Parser PR: [PHP 7.4] Add array spread nikic/PHP-Parser#609
• RFC: https://wiki.php.net/rfc/spread_operator_for_array
• array_merge of 2 items

[TomasVotruba]

https://stackoverflow.com/a/45420176/1348344