Implement PersistentValueMap, a map that stores UniquePersistent values.

src/global-handles.cc

 // Copyright 2009 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 217 matching lines @@
   }
 
   void MakeWeak(void* parameter, WeakCallback weak_callback) {
     ASSERT(weak_callback != NULL);
     ASSERT(state() != FREE);
     set_state(WEAK);
     set_parameter(parameter);
     weak_callback_ = weak_callback;
   }
 
-  void ClearWeakness() {
+  void* ClearWeakness() {
     ASSERT(state() != FREE);
+    void* p = parameter();
     set_state(NORMAL);
     set_parameter(NULL);
+    return p;
   }
 
   bool PostGarbageCollectionProcessing(Isolate* isolate) {
     if (state() != Node::PENDING) return false;
     if (weak_callback_ == NULL) {
       Release();
       return false;
     }
     void* par = parameter();
     set_state(NEAR_DEATH);
@@ skipping 243 matching lines @@
 }
 
 
 void GlobalHandles::MakeWeak(Object** location,
                              void* parameter,
                              WeakCallback weak_callback) {
   Node::FromLocation(location)->MakeWeak(parameter, weak_callback);
 }
 
 
-void GlobalHandles::ClearWeakness(Object** location) {
-  Node::FromLocation(location)->ClearWeakness();
+void* GlobalHandles::ClearWeakness(Object** location) {
+  return Node::FromLocation(location)->ClearWeakness();
 }
 
 
 void GlobalHandles::MarkIndependent(Object** location) {
   Node::FromLocation(location)->MarkIndependent();
 }
 
 
 void GlobalHandles::MarkPartiallyDependent(Object** location) {
   Node::FromLocation(location)->MarkPartiallyDependent();
@@ skipping 567 matching lines @@
   ASSERT_EQ(isolate->heap()->the_hole_value(), blocks_[block][offset]);
   blocks_[block][offset] = object;
   if (isolate->heap()->InNewSpace(object)) {
     new_space_indices_.Add(size_);
   }
   *index = size_++;
 }
 
 
 } }  // namespace v8::internal