Indentation doesn't work with } in comment.

```vala
public static void main(string[] args)
{
    int[] c = b[1:3];    // { 4, 6 }
{
    // something 
}
```

In the code, the last ``}`` in comment is automatically worked like a ``curly bracket right`` of main block, not like comment.
so indentation's been unbalanced as the code above.