resolve()/reject() on Promise subclasses and @@species

[Boris Zbarsky]

I was just implementing subclassing of Promise in Gecko, when I realized 
that given a Promise subclass MyPromise these two calls:

   MyPromise.race([])
   MyPromise.all([])

will take MyPromise[@@species] into account when creating the return 
value, but these two calls:

   MyPromise.resolve()
   MyPromise.reject()

will not; they will invoke MyPromise itself, not MyPromise[@@species].

This is because 
http://www.ecma-international.org/ecma-262/6.0/#sec-promise.all and 
http://www.ecma-international.org/ecma-262/6.0/#sec-promise.race do the 
whole @@species thing but 
http://www.ecma-international.org/ecma-262/6.0/#sec-promise.reject and 
http://www.ecma-international.org/ecma-262/6.0/#sec-promise.resolve do not.

Is this behavior intentional?  If so, I'd really like to understand the 
reason for it.

-Boris