I'm not sure, Glenn, and that is the best article I can find.
That article isn't from 2016. It's been updated most recently at the start of this year.
MDN is a really good metric to go by. Chrome and Firefox normally adhere to standards quite well, and Firefox's information applies fairly well to what ideally should and realistically is being done. IE, not sure, but in the past it hasn't always complied.
I'd go with the above, in that it's likely quite accurate, unless 1) 2018 is released (it won't be til end of this year, it seems) 2) there's something from ECMAScript itself. Not that there isn't any other info. now (the above is just the best I could find), so if anyone else has a better source, please post!
React does use ES2015 features, and it is listed as a prerequisite.
Angular uses TypeScript, doesn't technically have ES2015 as a prerequisite, but TypeScript and ES2015 share similar features; however, the Angular course (namely Accelerating; the 2 AngularJS, the other 2 courses with Angular in their title, are older versions that use es5) I found did a really good job of briefly explaining any TypeScript features that were used.
It sounds like you don't have to do the ES2015 course then like the other courses you listed, correct? I'd recommend keeping what I said above in mind for Angular and especially React, and do start those courses first, and if the need arises go to the ES2015 course for further explanation.