Some sub-package imports (ex: solid-js) not working

[FredKSchott]

Original Discussion: https://www.pika.dev/npm/snowpack/discuss/70
/cc @high1, @FredKSchott

// From the solid-js readme
import { render } from "solid-js/dom";
// This should work, but doesn't 
import { render } from "/web_modules/solid-js/dom.js";

It breaks because "node_modules/solid-js/dom" is a directory that only contains a package.json, that points to files back up in a different part of the package. It's the fact that this sub-package package.json specifically reaches up into its parent directory that breaks our resolver.

As a part of trying to figure out why exactly this was breaking, I think I found a good fix 😆PR incoming

[FredKSchott]

Fixed in #199