Introduce {ConstantElementsPair} struct for type safety.

src/objects-inl.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.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 5791 matching lines @@
 SMI_ACCESSORS(PrototypeInfo, bit_field, kBitFieldOffset)
 BOOL_ACCESSORS(PrototypeInfo, bit_field, should_be_fast_map, kShouldBeFastBit)
 
 ACCESSORS(Tuple2, value1, Object, kValue1Offset)
 ACCESSORS(Tuple2, value2, Object, kValue2Offset)
 ACCESSORS(Tuple3, value3, Object, kValue3Offset)
 
 ACCESSORS(ContextExtension, scope_info, ScopeInfo, kScopeInfoOffset)
 ACCESSORS(ContextExtension, extension, Object, kExtensionOffset)
 
+SMI_ACCESSORS(ConstantElementsPair, elements_kind, kElementsKindOffset)
+ACCESSORS(ConstantElementsPair, constant_values, FixedArrayBase,
+          kConstantValuesOffset)
+
 ACCESSORS(JSModuleNamespace, module, Module, kModuleOffset)
 
 ACCESSORS(JSFixedArrayIterator, array, FixedArray, kArrayOffset)
 SMI_ACCESSORS(JSFixedArrayIterator, index, kIndexOffset)
 ACCESSORS(JSFixedArrayIterator, initial_next, JSFunction, kNextOffset)
 
 ACCESSORS(Module, code, Object, kCodeOffset)
 ACCESSORS(Module, exports, ObjectHashTable, kExportsOffset)
 ACCESSORS(Module, regular_exports, FixedArray, kRegularExportsOffset)
 ACCESSORS(Module, regular_imports, FixedArray, kRegularImportsOffset)
@@ skipping 2663 matching lines @@
 #undef WRITE_INT64_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_INL_H_