Add zapping of disposed persistent handles.

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 95 matching lines @@
     set_state(NORMAL);
     parameter_or_next_free_.parameter = NULL;
     weak_reference_callback_ = NULL;
     near_death_callback_ = NULL;
     IncreaseBlockUses(global_handles);
   }
 
   void Release(GlobalHandles* global_handles) {
     ASSERT(state() != FREE);
     set_state(FREE);
+#ifdef DEBUG
+    // Zap the values for eager trapping.
+    object_ = NULL;
+    class_id_ = v8::HeapProfiler::kPersistentHandleNoClassId;
+    set_independent(false);
+    set_partially_dependent(false);
+    weak_reference_callback_ = NULL;
+    near_death_callback_ = NULL;
+#endif
     parameter_or_next_free_.next_free = global_handles->first_free_;
     global_handles->first_free_ = this;
     DecreaseBlockUses(global_handles);
   }
 
   // Object slot accessors.
   Object* object() const { return object_; }
   Object** location() { return &object_; }
   Handle<Object> handle() { return Handle<Object>(location()); }
 
@@ skipping 718 matching lines @@
   implicit_ref_groups_.Clear();
 }
 
 
 void GlobalHandles::TearDown() {
   // TODO(1428): invoke weak callbacks.
 }
 
 
 } }  // namespace v8::internal