Map::TransitionElementsTo() extracted from JSObject::GetElementsTransitionMap().

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 7eddc41977d0d335b4495072e17c365a57639651..0de2db26765f282cb62c779080b2add43f90339c 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -10040,12 +10040,9 @@ class ArrayConcatVisitor {
     Handle<JSArray> array = isolate_->factory()->NewJSArray(0);
     Handle<Object> length =
         isolate_->factory()->NewNumber(static_cast<double>(index_offset_));
-    Handle<Map> map;
-    if (fast_elements_) {
-      map = JSObject::GetElementsTransitionMap(array, FAST_HOLEY_ELEMENTS);
-    } else {
-      map = JSObject::GetElementsTransitionMap(array, DICTIONARY_ELEMENTS);
-    }
+    Handle<Map> map = JSObject::GetElementsTransitionMap(
+        array,
+        fast_elements_ ? FAST_HOLEY_ELEMENTS : DICTIONARY_ELEMENTS);
     array->set_map(*map);
     array->set_length(*length);
     array->set_elements(*storage_);