Support trailing comma after the last argument.

[linuxerwang]

Example:

function mergeObjects(x, y) { /* dummy body */}

mergeObjects(
    { "duck": "quack" },
    { "dog": "bark" }, // Allow trailing comma after the last argument.
);

[tlimoncelli]

Thank you so much! I've wanted this feature for years!

(Take a peek at https://github.com/StackExchange/dnscontrol/releases/tag/v4.15.0)