cmd/compile: does not compile correct program

``` go
package n
func n() {
    <-chan int((chan int)(nil))
}
```

```
$ go tool compile -oldparser /tmp/test.go
$ go tool compile /tmp/test.go
/tmp/test.go:3: syntax error: unexpected ( at end of statement
```

go version devel +25a28da Sun Nov 15 23:41:28 2015 +0000 linux/amd64
