Remove optional chaining usage

[chuntington]

This PR removes the use of optional chaining syntax to ensure compatibility with Node.js versions 13 and below.

For reference: 8293c2d#r63911585

[adamwathan]

Hey! This isn't necessary, we transpile all of our code to work for node 12 before publishing:

https://github.com/tailwindlabs/tailwindcss/blob/master/.swcrc

If you are hitting this when running locally or something you should make sure you are running the transpiled code:

https://github.com/tailwindlabs/tailwindcss/blob/master/package.json#L22

[chuntington]

Thanks for reaching out @adamwathan!

I'm running into issues using Node.js v12 and this configuration: https://github.com/chuntington/webpack-boilerplate/blob/master/postcss.config.js

In that project, do you know what should I do/change to run the transpiled code?

[RobinMalfait]

Hey!

Sorry this is my fault, I have a quick fix here and will do a proper fix tomorrow. In the meantime I'll get this merged and will release a new version so that it works again: #7077