Replace Traceur Compiler with 6to5

[alongubkin]

6to5 is an ES6 to ES5 compiler. But unlike Traceur compiler, it outputs clean code without runtime. We should use it instead of Traceur.

https://6to5.github.io/differences.html

[michaelstephendavies]

It does have a runtime: https://6to5.github.io/polyfill.html

[shfx]

👍

[Namek]

Nice to have for debugging in environment not supporting source mapping. By the way, which are such?

[zekesonxx]

6to5 has a polyfill and a runtime, the polyfill exists as a polyfill for ES6 features, and the runtime is just a replacement for code that would otherwise be placed at the top of the file.

I vote for this, as even though it still has the polyfill, it'll be a lot more pleasant. Additionally, typing 6to5 is much quicker than typing traceur.

[jamiebuilds]

Hi guys, I'm a contributor to 6to5. We'd love if spider used 6to5. If you need any help with this feel free to stop by our gitter room. If you have any specific questions about the differences between 6to5 and other transpilers let me know!

[zekesonxx]

Initial implementation: https://github.com/zekesonxx/spider/tree/es5-6to5