Stage-3 Packages

Ponyfill's for some native ES2017+ built-in methods

Transform the Import Attributes proposal (`import ... from '...' with { ... }`) to the previous version known as Import Assertions (`import ... from '...' assert { ... }`).

Transform source phase imports (`import source ... from '...'`) to work in browsers and Node.js, assuming that the imported source is a WebAssembly module.

Transform json modules imports (`import '...' with { type: 'json' }`) to work in browsers and Node.js.