[heap] Introduce HeapVisitor interface.

src/objects-body-descriptors.h

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_BODY_DESCRIPTORS_H_
 #define V8_OBJECTS_BODY_DESCRIPTORS_H_
 
 #include "src/objects.h"
 
 namespace v8 {
@@ skipping 83 matching lines @@
   template <typename StaticVisitor>
   static inline void IterateBody(HeapObject* obj) {
     Heap* heap = obj->GetHeap();
     IteratePointers<StaticVisitor>(heap, obj, start_offset, end_offset);
   }
 
   template <typename StaticVisitor>
   static inline void IterateBody(HeapObject* obj, int object_size) {
     IterateBody(obj);
   }
+
+  static inline int SizeOf(Map* map, HeapObject* object) { return kSize; }
 };
 
 
 // This class describes a body of an object of a variable size
 // in which all pointer fields are located in the [start_offset, object_size)
 // interval.
 template <int start_offset>
 class FlexibleBodyDescriptor final : public BodyDescriptorBase {
  public:
   static const int kStartOffset = start_offset;
@@ skipping 17 matching lines @@
   static inline int SizeOf(Map* map, HeapObject* object);
 };
 
 
 typedef FlexibleBodyDescriptor<HeapObject::kHeaderSize> StructBodyDescriptor;
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_BODY_DESCRIPTORS_H_