[turbofan] Introduce a TransitionElementsKind simplified operator.

src/runtime/runtime-array.cc

Index: src/runtime/runtime-array.cc
diff --git a/src/runtime/runtime-array.cc b/src/runtime/runtime-array.cc
index a92215c85d046ab8121dab8248d336c96e55fe15..68543d9a267c9c1473d12d3edbb89cab56a6accd 100644
--- a/src/runtime/runtime-array.cc
+++ b/src/runtime/runtime-array.cc
@@ -86,11 +86,12 @@ RUNTIME_FUNCTION(Runtime_FixedArraySet) {
 
 RUNTIME_FUNCTION(Runtime_TransitionElementsKind) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
-  CONVERT_ARG_HANDLE_CHECKED(JSArray, array, 0);
-  CONVERT_ARG_HANDLE_CHECKED(Map, map, 1);
-  JSObject::TransitionElementsKind(array, map->elements_kind());
-  return *array;
+  DCHECK_EQ(2, args.length());
+  CONVERT_ARG_HANDLE_CHECKED(JSArray, object, 0);
+  CONVERT_ARG_HANDLE_CHECKED(Map, to_map, 1);
+  ElementsKind to_kind = to_map->elements_kind();
+  ElementsAccessor::ForKind(to_kind)->TransitionElementsKind(object, to_map);
+  return *object;
 }