unhandledRejection algorithm incomplete

[jamestalmage]

var deferred = Promise.defer();
deferred
  .then()
  .then()  // only this one promise in the chain ends up getting marked as "handled"
  .catch(); 

[jamestalmage]

@sindresorhus @floatdrop

This is going to be pretty hard to do without potential memory leaks.

var a = promiseFn(..);
var b = a.then(..);
var c = a.then(..);

c.catch(..);  // A and C are now both handled, B is not.

I see no good way to do that without owner links, and that is going to make things tricky.