Add an API for enumerating persistent handles

src/global-handles.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 113 matching lines @@
   // handle.  When the garbage collector recognizes that only weak global
   // handles point to an object the handles are cleared and the callback
   // function is invoked (for each handle) with the handle and corresponding
   // parameter as arguments.  Note: cleared means set to Smi::FromInt(0). The
   // reason is that Smi::FromInt(0) does not change during garage collection.
   void MakeWeak(Object** location,
                 void* parameter,
                 WeakReferenceCallback callback);
 
   static void SetWrapperClassId(Object** location, uint16_t class_id);
+  static uint16_t GetWrapperClassId(Object** location);
 
   // Returns the current number of weak handles.
   int NumberOfWeakHandles() { return number_of_weak_handles_; }
 
   void RecordStats(HeapStats* stats);
 
   // Returns the current number of weak handles to global objects.
   // These handles are also included in NumberOfWeakHandles().
   int NumberOfGlobalObjectWeakHandles() {
     return number_of_global_object_weak_handles_;
   }
 
   // Returns the current number of handles to global objects.
   int NumberOfGlobalHandles() {
     return number_of_global_handles_;
   }
 
   // Clear the weakness of a global handle.
   void ClearWeakness(Object** location);
 
   // Clear the weakness of a global handle.
   void MarkIndependent(Object** location);
 
+  static bool IsIndependent(Object** location);
+
   // Tells whether global handle is near death.
   static bool IsNearDeath(Object** location);
 
   // Tells whether global handle is weak.
   static bool IsWeak(Object** location);
 
   // Process pending weak handles.
   // Returns true if next major GC is likely to collect more garbage.
   bool PostGarbageCollectionProcessing(GarbageCollector collector);
 
@@ skipping 109 matching lines @@
 
   friend class Isolate;
 
   DISALLOW_COPY_AND_ASSIGN(GlobalHandles);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_GLOBAL_HANDLES_H_