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

runtime/vm/object_store.h

 // 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.
 
 #ifndef VM_OBJECT_STORE_H_
 #define VM_OBJECT_STORE_H_
 
 #include "vm/object.h"
 
 namespace dart {
@@ skipping 54 matching lines @@
   }
 
   RawType* function_impl_type() const { return function_impl_type_; }
   void set_function_impl_type(const Type& value) {
     function_impl_type_ = value.raw();
   }
 
   RawClass* type_class() const { return type_class_; }
   void set_type_class(const Class& value) { type_class_ = value.raw(); }
 
+  RawClass* type_ref_class() const { return type_ref_class_; }
+  void set_type_ref_class(const Class& value) { type_ref_class_ = value.raw(); }
+
   RawClass* type_parameter_class() const { return type_parameter_class_; }
   void set_type_parameter_class(const Class& value) {
     type_parameter_class_ = value.raw();
   }
 
   RawClass* bounded_type_class() const { return bounded_type_class_; }
   void set_bounded_type_class(const Class& value) {
     bounded_type_class_ = value.raw();
   }
 
@@ skipping 329 matching lines @@
   ObjectStore();
 
   RawObject** from() { return reinterpret_cast<RawObject**>(&object_class_); }
   RawClass* object_class_;
   RawType* object_type_;
   RawClass* null_class_;
   RawType* null_type_;
   RawType* function_type_;
   RawType* function_impl_type_;
   RawClass* type_class_;
+  RawClass* type_ref_class_;
   RawClass* type_parameter_class_;
   RawClass* bounded_type_class_;
   RawClass* mixin_app_type_class_;
   RawType* number_type_;
   RawType* int_type_;
   RawClass* integer_implementation_class_;
   RawClass* smi_class_;
   RawType* smi_type_;
   RawClass* mint_class_;
   RawType* mint_type_;
@@ skipping 52 matching lines @@
   }
 
   friend class SnapshotReader;
 
   DISALLOW_COPY_AND_ASSIGN(ObjectStore);
 };
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_STORE_H_