Fix circular dependency in Node polyfills

[eigendude]

Description

This PR contains the fix in nodejs/readable-stream#458 hand-applied to the several polyfills in this repo. From the other PR's description:

This PR fixes a circular dependency that has been affecting the rollup ecosystem for a long time. The fix is simple, as the circularity comes from a single type test that can be simply replaced with a boolean. (And the boolean already exists, it's just exposed to the Duplex child class now).

The root cause is due to rollup's handling of hoisting. Duplex inherits from Readable and Writable, but Readable and Writable check for Duplex-ity, ergo circular. As a result, when Duplex inherits from Readable/Writable, these two classes are hoisted but not yet defined.

The fix is simple: Replace the Duplex-ity test with a boolean, set by Duplex when it constructs its base classes.

This boolean actually already exists locally in both Readable and Writable, so it makes sense to use it to bust the circular dependency.

How has this been tested?

I applied the patch to my Snowpack project after installing npm modules. I added the following to my snowpack.config.cjs file:

const polyfills = require("rollup-plugin-node-polyfills");

module.exports = {
  ...
  packageOptions: {
    rollup: {
      plugins: [
        ...
        polyfills(),
        ...
      ],
    },
  },
};

I started the live server. No errors observed.

Related PRs

See nodejs/readable-stream#458

[eigendude]

The Rollup ecosystem has advanced considerably from the last two years, seeing the deprecation of Snowpack and the broader adoption of Vite. As such, these polyfills are unlikely to be needed going forward.