Fix Array.prototype.concat for arguments object with getter.

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 b5655db611a5ce34161d45990718872fa7f02916..e9532ac814300fd1ef237ffbaf8b12777050bcbc 100644
--- a/src/runtime/runtime-array.cc
+++ b/src/runtime/runtime-array.cc
@@ -437,12 +437,8 @@ static void CollectElementIndices(Handle<JSObject> object, uint32_t range,
       }
     case FAST_SLOPPY_ARGUMENTS_ELEMENTS:
     case SLOW_SLOPPY_ARGUMENTS_ELEMENTS: {
-      MaybeHandle<Object> length_obj =
-          Object::GetProperty(object, isolate->factory()->length_string());
-      double length_num = length_obj.ToHandleChecked()->Number();
-      uint32_t length = static_cast<uint32_t>(DoubleToInt32(length_num));
       ElementsAccessor* accessor = object->GetElementsAccessor();
-      for (uint32_t i = 0; i < length; i++) {
+      for (uint32_t i = 0; i < range; i++) {
         if (accessor->HasElement(object, i)) {
           indices->Add(i);
         }