[skrebbel]

Meh, the ES6 features this needs don't need transpilation, just Promises. They're perfectly well stubbable with a library (such as Core-js or Bluebird) so you don't actually need to transpile stuff "again" to ES5.

But note that it's shipped as a babel plugin, so you shouldn't even need to care.

What this really is is "use the currently-most-popular JS transformation toolchain to transform cool-JS to works-in-browser-JS". Whether part X is in the ES6 standard and part Y might end up in ES7 is really mostly besides the point.