Only zapped used handles if a handle scope fits entirely within one handle block

src/handles-inl.h

 // Copyright 2006-2008 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 112 matching lines @@
   CloseScope(isolate_, prev_next_, prev_limit_);
 }
 
 
 void HandleScope::CloseScope(Isolate* isolate,
                              Object** prev_next,
                              Object** prev_limit) {
   v8::ImplementationUtilities::HandleScopeData* current =
       isolate->handle_scope_data();
 
-  current->next = prev_next;
+  std::swap(current->next,  prev_next);

[Michael Starzinger, 2013/09/27 11:24:30]

nit: Two white-spaces after comma.

   current->level--;
   if (current->limit != prev_limit) {
     current->limit = prev_limit;
     DeleteExtensions(isolate);
+#ifdef ENABLE_EXTRA_CHECKS
+    ZapRange(current->next, prev_limit);
+  } else {
+    ZapRange(current->next, prev_next);
+#endif
   }
-
-#ifdef ENABLE_EXTRA_CHECKS
-  ZapRange(prev_next, prev_limit);
-#endif
 }
 
 
 template <typename T>
 Handle<T> HandleScope::CloseAndEscape(Handle<T> handle_value) {
   v8::ImplementationUtilities::HandleScopeData* current =
       isolate_->handle_scope_data();
 
   T* value = *handle_value;
   // Throw away all handles in the current scope.
@@ skipping 53 matching lines @@
   current->level = level_;
   ASSERT_EQ(current->next, current->limit);
   current->limit = limit_;
 }
 
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_HANDLES_INL_H_