Formatting result of const-generic args in supertraits causes compile-error

rustfmt wrongly formats this
```rust
pub trait Foo: Bar<{Baz::COUNT}> {
	const ASD: usize;
}
```
like this:
```rust
pub trait Foo: Bar<{ Baz::COUNT }> {
	Baz::COUNT}> {
	const ASD: usize;
}
```

which is really bad because this misformatting prevents compilation!