Bad span for try shorthand

The span associated to the expression in

``` rust
fn test() {
    a?
}
```

includes the closing brace, which it should not.

Found this after @erikjohnson mentioned a fatal error in rustfmt [here](https://github.com/rust-lang-nursery/rustfmt/pull/893).

I'm working on a patch for this.
