Suggestion: 'for..of'

[RyanCavanaugh]

Implement TypeScript support for the for-of loop as described in the ES6 proposal

Reference: https://github.com/dherman/tc39-codex-wiki/blob/master/data/es6/for-of/index.md

To be determined: What cases can we support code generation for when targeting pre-ES6 targets?

[DickvdBrink]

I guess this is #2207 and #2164 (the latter ins't merged yet)
Edit: The links to the issues is just so it is easier to find this one because of the GitHub links in the other issues. So people can close this one when the other is merged :)

[danquirk]

Yep, thanks, we'll close this when we finish adding the type check work for downlevel.