Do not use new struct type where unnecessary.

src/objects/literal-objects.h

 // Copyright 2017 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_LITERAL_OBJECTS_H_
 #define V8_OBJECTS_LITERAL_OBJECTS_H_
 
 #include "src/objects.h"
 
 // Has to be the last include (doesn't have include guards):
@@ skipping 22 matching lines @@
 
   DECLARE_CAST(BoilerplateDescription)
 
  private:
   bool has_number_of_properties() const;
 };
 
 // Pair of {ElementsKind} and an array of constant values for {ArrayLiteral}
 // expressions. Used to communicate with the runtime for literal boilerplate
 // creation within the {Runtime_CreateArrayLiteral} method.
-class ConstantElementsPair : public Struct {
+class ConstantElementsPair : public Tuple2 {
  public:
   DECL_INT_ACCESSORS(elements_kind)
   DECL_ACCESSORS(constant_values, FixedArrayBase)
 
   DECLARE_CAST(ConstantElementsPair)
 
-  // Dispatched behavior.
-  DECLARE_PRINTER(ConstantElementsPair)
-  DECLARE_VERIFIER(ConstantElementsPair)
-
-  static const int kElementsKindOffset = HeapObject::kHeaderSize;
-  static const int kConstantValuesOffset = kElementsKindOffset + kPointerSize;
-  static const int kSize = kConstantValuesOffset + kPointerSize;
+  static const int kElementsKindOffset = kValue1Offset;
+  static const int kConstantValuesOffset = kValue2Offset;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ConstantElementsPair);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #include "src/objects/object-macros-undef.h"
 
 #endif  // V8_OBJECTS_LITERAL_OBJECTS_H_