"ECMA TC39", not "Emca TC39". Also, looks like a bad markup link for TC39. Also note that it's either "co-authored by Mozilla, Apple, Moddable and Sony" or "authored by Guo along with others from Mozilla, Apple, Moddable and Sony", but directly related to that statement, that makes this "not a Google proposal" but clearly an "industry proposal" if it has Mozilla and Apple buy-in.

Also, "the proposed solution is not to backtrack on existing features" makes very little sense. If you're going to split something into core and "compiles down to core", then a LOT of features can be moved out of core because they're just (definitely worth keeping, but not necessary in core if that split were made) convenience APIs.