Fix named types being defined to named types. In general, the

code assumes that the definition of a named type is not a
named type, but some code paths could violate that.

R=rsc
APPROVED=rsc
DELTA=9  (5 added, 2 deleted, 2 changed)
OCL=34046
CL=34053

usr/austin/eval/scope.go

@@ -85,12 +85,10 @@ func (b *block) DefineType(name string, pos token.Position, t Type) Type {
 	if _, ok := b.defs[name]; ok {
 		return nil;
 	}
-	// We take the representative type of t because multiple
-	// levels of naming are useless.
+	nt := &NamedType{pos, name, nil, true, make(map[string] Method)};
 	if t != nil {
-		t = t.lit();
+		nt.Complete(t);
 	}
-	nt := &NamedType{pos, name, t, false, make(map[string] Method)};
 	b.defs[name] = nt;
 	return nt;
 }

usr/austin/eval/type.go

@@ -980,6 +980,11 @@ func (t *NamedType) Complete(def Type) {
 	if !t.incomplete {
 		log.Crashf("cannot complete already completed NamedType %+v", *t);
 	}
+	// We strip the name from def because multiple levels of
+	// naming are useless.
+	if ndef, ok := def.(*NamedType); ok {
+		def = ndef.Def;
+	}
 	t.Def = def;
 	t.incomplete = false;
 }