Introduce class TypeRef in the VM to fully support recursive types.

runtime/vm/snapshot.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/snapshot.h"
 
 #include "platform/assert.h"
 #include "vm/bigint_operations.h"
 #include "vm/bootstrap.h"
 #include "vm/class_finalizer.h"
@@ skipping 518 matching lines @@
 RawUnresolvedClass* SnapshotReader::NewUnresolvedClass() {
   ALLOC_NEW_OBJECT(UnresolvedClass, Object::unresolved_class_class());
 }
 
 
 RawType* SnapshotReader::NewType() {
   ALLOC_NEW_OBJECT(Type, object_store()->type_class());
 }
 
 
+RawTypeRef* SnapshotReader::NewTypeRef() {
+  ALLOC_NEW_OBJECT(TypeRef, object_store()->type_ref_class());
+}
+
+
 RawTypeParameter* SnapshotReader::NewTypeParameter() {
   ALLOC_NEW_OBJECT(TypeParameter, object_store()->type_parameter_class());
 }
 
 
 RawBoundedType* SnapshotReader::NewBoundedType() {
   ALLOC_NEW_OBJECT(BoundedType, object_store()->bounded_type_class());
 }
 
 
@@ skipping 967 matching lines @@
     UnmarkAll();
     isolate->set_long_jump_base(base);
   } else {
     isolate->set_long_jump_base(base);
     ThrowException(exception_type(), exception_msg());
   }
 }
 
 
 }  // namespace dart