Introduce {ConstantElementsPair} struct for type safety.

src/ast/ast.cc

 // 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.
 
 #include "src/ast/ast.h"
 
 #include <cmath>  // For isfinite.
 
 #include "src/ast/compile-time-value.h"
 #include "src/ast/prettyprinter.h"
@@ skipping 619 matching lines @@
 
   Handle<FixedArrayBase> elements = fixed_array;
   if (IsFastDoubleElementsKind(kind)) {
     ElementsAccessor* accessor = ElementsAccessor::ForKind(kind);
     elements = isolate->factory()->NewFixedDoubleArray(constants_length);
     // We are copying from non-fast-double to fast-double.
     ElementsKind from_kind = TERMINAL_FAST_ELEMENTS_KIND;
     accessor->CopyElements(fixed_array, from_kind, elements, constants_length);
   }
 
-  // Remember both the literal's constant values as well as the ElementsKind
-  // in a 2-element FixedArray.
-  Handle<FixedArray> literals = isolate->factory()->NewFixedArray(2, TENURED);
-  literals->set(0, Smi::FromInt(kind));
-  literals->set(1, *elements);
+  // Remember both the literal's constant values as well as the ElementsKind.
+  Handle<ConstantElementsPair> literals =
+      isolate->factory()->NewConstantElementsPair(kind, elements);
 
   constant_elements_ = literals;
   set_is_simple(is_simple);
   set_depth(depth_acc);
 }
 
 
 void ArrayLiteral::AssignFeedbackVectorSlots(Isolate* isolate,
                                              FeedbackVectorSpec* spec,
                                              FeedbackVectorSlotCache* cache) {
@@ skipping 292 matching lines @@
 // static
 bool Literal::Match(void* literal1, void* literal2) {
   const AstValue* x = static_cast<Literal*>(literal1)->raw_value();
   const AstValue* y = static_cast<Literal*>(literal2)->raw_value();
   return (x->IsString() && y->IsString() && x->AsString() == y->AsString()) ||
          (x->IsNumber() && y->IsNumber() && x->AsNumber() == y->AsNumber());
 }
 
 }  // namespace internal
 }  // namespace v8