Substitution for type variables in mirrors on instantiated generics.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 07cc2a89aad1d91de790042d403be4b8fa571e47..c9e355d0075c15ab86a4a65a183dae37d876a3d6 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -1538,13 +1538,14 @@ RawType* Class::SignatureType() const {
 }
 
 
-RawType* Class::RareType() const {
+RawAbstractType* Class::RareType() const {
   const Type& type = Type::Handle(Type::New(
       *this,
       Object::null_abstract_type_arguments(),
       Scanner::kDummyTokenIndex));
-  return Type::RawCast(
-      ClassFinalizer::FinalizeType(*this, type, ClassFinalizer::kCanonicalize));
+  return ClassFinalizer::FinalizeType(*this,
+                                      type,
+                                      ClassFinalizer::kCanonicalize);
 }