1. Provide a framework to traverse persistent prolog weak handles.

runtime/vm/object.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_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 3997 matching lines @@
                     Error* bound_error) const;
 
   // Check whether this instance is identical to the argument according to the
   // specification of dare:core's identical().
   bool IsIdenticalTo(const Instance& other) const;
 
   bool IsValidNativeIndex(int index) const {
     return ((index >= 0) && (index < clazz()->ptr()->num_native_fields_));
   }
 
+  intptr_t* NativeFieldsDataAddr() const;
   inline intptr_t GetNativeField(int index) const;
   inline void GetNativeFields(uint16_t num_fields,
                               intptr_t* field_values) const;
 
   uint16_t NumNativeFields() const {
     return clazz()->ptr()->num_native_fields_;
   }
 
   void SetNativeField(int index, intptr_t value) const;
 
@@ skipping 24 matching lines @@
   RawObject** FieldAddrAtOffset(intptr_t offset) const {
     ASSERT(IsValidFieldOffset(offset));
     return reinterpret_cast<RawObject**>(raw_value() - kHeapObjectTag + offset);
   }
   RawObject** FieldAddr(const Field& field) const {
     return FieldAddrAtOffset(field.Offset());
   }
   RawObject** NativeFieldsAddr() const {
     return FieldAddrAtOffset(sizeof(RawObject));
   }
+
   void SetFieldAtOffset(intptr_t offset, const Object& value) const {
     StorePointer(FieldAddrAtOffset(offset), value.raw());
   }
   bool IsValidFieldOffset(intptr_t offset) const;
 
   static intptr_t NextFieldOffset() {
     return sizeof(RawInstance);
   }
 
   // TODO(iposva): Determine if this gets in the way of Smi.
@@ skipping 2703 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_