[objects] do not visit ArrayBuffer's backing store

src/objects.h

 // Copyright 2012 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.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 9645 matching lines @@
 
   static bool SetupAllocatingData(Handle<JSArrayBuffer> array_buffer,
                                   Isolate* isolate, size_t allocated_length,
                                   bool initialize = true,
                                   SharedFlag shared = SharedFlag::kNotShared);
 
   // Dispatched behavior.
   DECLARE_PRINTER(JSArrayBuffer)
   DECLARE_VERIFIER(JSArrayBuffer)
 
-  static const int kBackingStoreOffset = JSObject::kHeaderSize;
-  static const int kByteLengthOffset = kBackingStoreOffset + kPointerSize;
-  static const int kBitFieldSlot = kByteLengthOffset + kPointerSize;
+  static const int kByteLengthOffset = JSObject::kHeaderSize;
+
+  // NOTE: GC will visit objects fields:
+  // 1. From JSObject::BodyDescriptor::kStartOffset to kByteLengthOffset +
+  //    kPointerSize
+  // 2. From start of the internal fields and up to the end of them
+  static const int kBackingStoreOffset = kByteLengthOffset + kPointerSize;
+  static const int kBitFieldSlot = kBackingStoreOffset + kPointerSize;
 #if V8_TARGET_LITTLE_ENDIAN || !V8_HOST_ARCH_64_BIT
   static const int kBitFieldOffset = kBitFieldSlot;
 #else
   static const int kBitFieldOffset = kBitFieldSlot + kIntSize;
 #endif
   static const int kSize = kBitFieldSlot + kPointerSize;
 
   static const int kSizeWithInternalFields =
       kSize + v8::ArrayBuffer::kInternalFieldCount * kPointerSize;
 
+  template <typename StaticVisitor>
+  static inline void JSArrayBufferIterateBody(Heap* heap, HeapObject* obj);
+
+  static inline void JSArrayBufferIterateBody(HeapObject* obj,
+                                              ObjectVisitor* v);
+
   class IsExternal : public BitField<bool, 1, 1> {};
   class IsNeuterable : public BitField<bool, 2, 1> {};
   class WasNeutered : public BitField<bool, 3, 1> {};
   class IsShared : public BitField<bool, 4, 1> {};
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSArrayBuffer);
 };
 
 
@@ skipping 777 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_