[api] Bring back finalizers on global handles

src/global-handles.h

 // Copyright 2011 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_GLOBAL_HANDLES_H_
 #define V8_GLOBAL_HANDLES_H_
 
 #include "include/v8.h"
 #include "include/v8-profiler.h"
 
@@ skipping 78 matching lines @@
   }
 
   bool operator<(const ObjectGroupRetainerInfo& other) const {
     return id < other.id;
   }
 
   UniqueId id;
   RetainedObjectInfo* info;
 };
 
-
 enum WeaknessType {
   NORMAL_WEAK,  // Embedder gets a handle to the dying object.
   // In the following cases, the embedder gets the parameter they passed in
   // earlier, and 0 or 2 first internal fields. Note that the internal
   // fields must contain aligned non-V8 pointers.  Getting pointers to V8
   // objects through this interface would be GC unsafe so in that case the
   // embedder gets a null pointer instead.
   PHANTOM_WEAK,
-  PHANTOM_WEAK_2_INTERNAL_FIELDS
+  PHANTOM_WEAK_2_INTERNAL_FIELDS,
+  // Like NORMAL_WEAK, but uses WeakCallbackInfo instead of WeakCallbackData.
+  FINALIZER_WEAK,
 };
 
-
 class GlobalHandles {
  public:
   ~GlobalHandles();
 
   // Creates a new global handle that is alive until Destroy is called.
   Handle<Object> Create(Object* value);
 
   // Copy a global handle
   static Handle<Object> CopyGlobal(Object** location);
 
@@ skipping 333 matching lines @@
   int singleton_handles_[NUMBER_OF_SINGLETON_HANDLES];
 
   DISALLOW_COPY_AND_ASSIGN(EternalHandles);
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_GLOBAL_HANDLES_H_