Buffer.from can take a Uint8Array

[reviewher]

This appears to be an oversight in the node.js documentation. Tracking issue nodejs/node#14118 .

The first part of the fix involves the Uint8Array case for Buffer.from:

static from(value: Uint8Array): Buffer;

The second part involves the original Buffer case. Since Buffer extends Uint8Array, the Uint8Array case also covers Buffer, so it might make sense to just remove static from(value: Buffer): Buffer; entirely