Vim indentation broken with commented struct fields.

Consider the following code:

``` rust
struct A {
    b: int,
    //
    c: int,
}
```

Opening a new line while on the `c`-line puts the cursor here:

``` rust
struct A {
    b: int,
    //
    c: int,
           X
}
```

I'm using the indent file from master.
