Upstreaming: Ignoring annotations on wildcards and type parameters themselves

[cpovirk]

(as opposed to on their bounds)

• 1db27ba
• 235b632

As the latter commit explains, I quite possibly could have done this in our TypeAnnotator if I'd been thinking. That way, we wouldn't need to modify CF.

That said, this change isn't too important, since we already report an error for such annotations. But if they appear in unchecked code or if users suppress the error, it would be nice for them to still have no effect.