[Runtime] Use ElementsAccessor in NewWithSpread.

src/runtime/runtime-classes.cc

 // 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.
 
 #include "src/runtime/runtime-utils.h"
 
 #include <stdlib.h>
 #include <limits>
 
 #include "src/accessors.h"
 #include "src/arguments.h"
 #include "src/debug/debug.h"
+#include "src/elements.h"
 #include "src/frames-inl.h"
 #include "src/isolate-inl.h"
 #include "src/messages.h"
 #include "src/runtime/runtime.h"
 
 namespace v8 {
 namespace internal {
 
 
 RUNTIME_FUNCTION(Runtime_ThrowNonMethodError) {
@@ skipping 425 matching lines @@
   CHECK(spread_array->length()->ToArrayIndex(&spread_length));
   int result_length = constructor_argc - 1 + spread_length;
   ScopedVector<Handle<Object>> construct_args(result_length);
 
   // Append each of the individual args to the result.
   for (int i = 0; i < constructor_argc - 1; i++) {
     construct_args[i] = args.at<Object>(2 + i);
   }
 
   // Append element of the spread to the result.
+  ElementsAccessor* accessor = spread_array->GetElementsAccessor();
   for (uint32_t i = 0; i < spread_length; i++) {
-    // TODO(petermarshall): Use ElementAccessors here.
-    LookupIterator it(isolate, spread, i);
-    Handle<Object> element = spread_array->GetDataProperty(&it);
+    DCHECK(accessor->HasElement(spread_array, i));
+    Handle<Object> element = accessor->Get(spread_array, i);
     construct_args[constructor_argc - 1 + i] = element;
   }
 
   // Call the constructor.
   RETURN_RESULT_OR_FAILURE(
       isolate, Execution::New(isolate, constructor, new_target, result_length,
                               construct_args.start()));
 }
 
 }  // namespace internal
 }  // namespace v8