LayoutDescriptor should inherit from JSTypedArray

src/layout-descriptor.h

 // Copyright 2014 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_LAYOUT_DESCRIPTOR_H_
 #define V8_LAYOUT_DESCRIPTOR_H_
 
 #include <iosfwd>
 
 #include "src/objects.h"
 
 namespace v8 {
 namespace internal {
 
 // LayoutDescriptor is a bit vector defining which fields contain non-tagged
 // values. It could either be a fixed typed array (slow form) or a Smi
 // if the length fits (fast form).
 // Each bit in the layout represents a FIELD. The bits are referenced by
 // field_index which is a field number. If the bit is set then the corresponding
 // field contains a non-tagged value and therefore must be skipped by GC.
 // Otherwise the field is considered tagged. If the queried bit lays "outside"
 // of the descriptor then the field is also considered tagged.
 // Once a layout descriptor is created it is allowed only to append properties
 // to it.
-class LayoutDescriptor : public FixedTypedArray<Uint32ArrayTraits> {
+class LayoutDescriptor : public JSTypedArray {
  public:
   V8_INLINE bool IsTagged(int field_index);
 
   // Queries the contiguous region of fields that are either tagged or not.
   // Returns true if the given field is tagged or false otherwise and writes
   // the length of the contiguous region to |out_sequence_length|.
   // If the sequence is longer than |max_sequence_length| then
   // |out_sequence_length| is set to |max_sequence_length|.
   bool IsTagged(int field_index, int max_sequence_length,
                 int* out_sequence_length);
@@ skipping 46 matching lines @@
 #ifdef OBJECT_PRINT
   // For our gdb macros, we should perhaps change these in the future.
   void Print();
 
   void Print(std::ostream& os);  // NOLINT
 #endif
 
   // Capacity of layout descriptors in bits.
   V8_INLINE int capacity();
 
+  V8_INLINE uint32_t get_scalar(int index);
+  V8_INLINE void set(int index, uint32_t value);
+
   static Handle<LayoutDescriptor> NewForTesting(Isolate* isolate, int length);
   LayoutDescriptor* SetTaggedForTesting(int field_index, bool tagged);
 
  private:
   static const int kNumberOfBits = 32;
 
   V8_INLINE static Handle<LayoutDescriptor> New(Isolate* isolate, int length);
   V8_INLINE static LayoutDescriptor* FromSmi(Smi* smi);
 
   V8_INLINE static bool InobjectUnboxedField(int inobject_properties,
@@ skipping 50 matching lines @@
 
  private:
   bool all_fields_tagged_;
   int header_size_;
   LayoutDescriptor* layout_descriptor_;
 };
 }
 }  // namespace v8::internal
 
 #endif  // V8_LAYOUT_DESCRIPTOR_H_