If you can’t bother to write the if statement that guarantees backward compatibility and follows a defined standard in use for almost 20 years, you are a horrid engineer IMO.
This is why there’s a general trend toward all things becoming complicated, brittle, and shitty.
If you're not using a compiler, you should definitely not use the latest and greatest features, unless you are well aware that you will not be supporting older browsers.
And in this case you can simply do an if statement with (first && first.second && first.second.third)
My point being, writing one long line is how the language inherently works. Use that instead of the new feature that only ships in new browsers. I’d still be upset if one of my teammates added an entire bundling system so they can simply write fewer lines for such simple menial aspects of the code. Forest for the trees.