ASify

[dcodeIO]

This PR investigates what's necessary to make the compiler sources compatible with asc.

• Add temporary fillers for Map#keys, Map#values and Set#values
• Investigate property names conflicting with keywords, like module.if(...)
• Convert abstract methods to trapping stubs
• Investigate problems with field initializers referring to a super field, like kind = NodeKind.IF
• Find a way to make binaryen.d.ts portable
• Investigate duplicate module exports
• Refactor src/builtins.ts (can't switch over strings)
• Finish the remaining 200 or so builtin comments 🚀

For those interested: npm run asbuild && npm run astest

Issues found:

• Investigate logical expression type rules
• Investigate contextual type propagation on initializers
• Investigate terminate state after infinite loop with return
• Investigate randomly failing non-null checks
• Investigate missing export * exports

Goal is that we can integrate a new step into CI as a test whether PRs conform to portable AS, even though it is unlikely that we'll get a working Wasm variant out of this already.

Update: As it turned out the Wasm binary is deemed valid by Binaryen and instantiates just fine, which is already more than what I expected. One can also call its exports, like provide and let it parse a file, but it ultimately fails when trying to compile a program due to virtual calls not yet being implemented, calling the wrong methods. More problems expected once we implement that, but so far I call that a success :)