Self fails to implement current trait in a default method

[huonw]

trait Foo {
    fn foo(&self) {
        bar(self)
    }
}

fn bar<F: Foo>(_: &F) {}

fn main(){}

dm2.rs:3:8: 3:11 error: failed to find an implementation of trait Foo for Self
dm2.rs:3         bar(self)
                 ^~~

Presumably Self : Foo in a default method on Foo.

(Part of #2794.)

[huonw]

Whoops, dup of #7183.