no warning when using const out of strict mode

[tejasmanohar]

I get this warning-
SyntaxError: Block-scoped declarations (let, const, function, class) not yet supported outside strict mode
when I use let out of strict mode but no warning when I use const out of it? the docs here say const is only available in strict-mode as well? https://nodejs.org/en/docs/es6/

I see that I don't get a SyntaxError when mutating variables declared w/ const out of strict mode anyhow, but that part is reasonable.

[tejasmanohar]

see #230. @targos has clarified this here- koajs/koa#501 (comment). i'll keep this issue open till that's merged (or resolved in another way).

[bnoordhuis]

I'm going to close this. let/const in sloppy mode is a V8 issue. Work is underway upstream to implement the ES6 semantics and that will eventually make its way into node.js.