Conditionally import 'window' package when `globalThis` is missing

[davejsdev]

Proposal

Summary

The window package adds unnecessary weight in browser contexts. We can conditionally import this based on if it's a node or browser env.

I'm not sure the best approach here that preserves the types of globalThis though. There are a few possible options. Right now, I'm considering having separate entry points depending on the env:

import { ... } from 'cssom-gen'; // default is the browser version

import { ... } from 'cssom-gen/node'; // sub-path for node imports

There's also conditional imports, but that's potentially messy supporting both CJS/ESM. I don't like it much.

Open to suggestions or PRs from anyone!