Jordan Harband (2015-01-27T22:55:22.000Z)
d at domenic.me (2015-02-13T23:25:37.444Z)
They are not - if they were, then adding a new well-known symbol like Symbol.foo would fail if anyone had code that did `Symbol.for('foo')`. (I have no idea if that is the reason, but certainly that's a reason not to make them available via the registry)