Reland of "[heap] Fine-grained JSArrayBuffer tracking"

src/heap/scavenger.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/heap/scavenger.h"
 
 #include "src/contexts.h"
 #include "src/heap/heap.h"
 #include "src/heap/objects-visiting-inl.h"
 #include "src/heap/scavenger-inl.h"
@@ skipping 277 matching lines @@
     int object_size = reinterpret_cast<FixedFloat64Array*>(object)->size();
     EvacuateObject<POINTER_OBJECT, kDoubleAligned>(map, slot, object,
                                                    object_size, promotion_mode);
   }
 
   static inline void EvacuateJSArrayBuffer(Map* map, HeapObject** slot,
                                            HeapObject* object,
                                            PromotionMode promotion_mode) {
     ObjectEvacuationStrategy<POINTER_OBJECT>::Visit(map, slot, object,
                                                     promotion_mode);
-
-    Heap* heap = map->GetHeap();
-    MapWord map_word = object->map_word();
-    DCHECK(map_word.IsForwardingAddress());
-    HeapObject* target = map_word.ToForwardingAddress();
-    if (!heap->InNewSpace(target)) {
-      heap->array_buffer_tracker()->Promote(JSArrayBuffer::cast(target));
-    }
   }
 
   static inline void EvacuateByteArray(Map* map, HeapObject** slot,
                                        HeapObject* object,
                                        PromotionMode promotion_mode) {
     int object_size = reinterpret_cast<ByteArray*>(object)->ByteArraySize();
     EvacuateObject<DATA_OBJECT, kWordAligned>(map, slot, object, object_size,
                                               promotion_mode);
   }
 
@@ skipping 162 matching lines @@
 
 void ScavengeVisitor::ScavengePointer(Object** p) {
   Object* object = *p;
   if (!heap_->InNewSpace(object)) return;
   Scavenger::ScavengeObject(reinterpret_cast<HeapObject**>(p),
                             reinterpret_cast<HeapObject*>(object));
 }
 
 }  // namespace internal
 }  // namespace v8