Type quotes and a splice is incorrectly typed causing runtime error

Consider the simple file `A.scala`.

```
object Macros {
   inline def q : Int = ${ '[ Int ] }
   val x : Int = 1 + q
}
```

Running `dotc A.scala` causes a runtime failure. 

The program is bogus because splicing a type does not yield a value of that type. The splice should instead result in a type. 
