Clear recorded slots when making a string external.

src/objects.cc

 // Copyright 2015 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.
 
 #include "src/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <memory>
 #include <sstream>
@@ skipping 2075 matching lines @@
   } else {
     new_map = is_internalized
                   ? heap->external_one_byte_internalized_string_map()
                   : heap->external_one_byte_string_map();
   }
 
   // Byte size of the external String object.
   int new_size = this->SizeFromMap(new_map);
   heap->CreateFillerObjectAt(this->address() + new_size, size - new_size,
                              ClearRecordedSlots::kNo);
+  heap->ClearRecordedSlotRange(this->address(), this->address() + new_size);
 
   // We are storing the new map using release store after creating a filler for
   // the left-over space to avoid races with the sweeper thread.
   this->synchronized_set_map(new_map);
 
   ExternalOneByteString* self = ExternalOneByteString::cast(this);
   self->set_resource(resource);
   if (is_internalized) self->Hash();  // Force regeneration of the hash value.
 
   heap->AdjustLiveBytes(this, new_size - size, Heap::CONCURRENT_TO_SWEEPER);
@@ skipping 16921 matching lines @@
   for (PrototypeIterator iter(isolate, this, kStartAtReceiver,
                               PrototypeIterator::END_AT_NULL);
        !iter.IsAtEnd(); iter.AdvanceIgnoringProxies()) {
     if (iter.GetCurrent<Object>()->IsJSProxy()) return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8