Add a generic remembered set class.

src/heap/heap.h

 // Copyright 2012 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_HEAP_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 273 matching lines @@
 class HeapStats;
 class HistogramTimer;
 class InlineAllocationObserver;
 class Isolate;
 class MemoryReducer;
 class ObjectStats;
 class Scavenger;
 class ScavengeJob;
 class WeakObjectRetainer;
 
+typedef void (*ObjectSlotCallback)(HeapObject** from, HeapObject* to);
 
 // A queue of objects promoted during scavenge. Each object is accompanied
 // by it's size to avoid dereferencing a map pointer for scanning.
 // The last page in to-space is used for the promotion queue. On conflict
 // during scavenge, the promotion queue is allocated externally and all
 // entries are copied to the external queue.
 class PromotionQueue {
  public:
   explicit PromotionQueue(Heap* heap)
       : front_(NULL),
@@ skipping 2326 matching lines @@
 
  private:
   friend class NewSpace;
   DISALLOW_COPY_AND_ASSIGN(InlineAllocationObserver);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_H_