ICE: Default methods and `&Self`

[alexcrichton]

The following code gives an ICE:

trait Foo {
    fn foo(&Self) {}
}
fn main() {
}

with the message:

rust: task failed at 'index out of bounds: the len is 0 but the index is 0', /Users/alex/code/rust-opt/src/librustc/middle/liveness.rs:1598

ping @msullivan

[alexcrichton]

I also then realized that this code doesn't parse:

trait Foo {
    fn foo(_: &Self) {}
}
fn main() {
}

[msullivan]

Hm. This is the same bugs as #8468 and #8417. This was first, but I didn't notice it, so closing it as a dupe.