[async-iteration] implement Async-from-Sync Iterator

src/objects.cc

 // Copyright 2015 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/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <memory>
 #include <sstream>
@@ skipping 12497 matching lines @@
 
 
 #ifdef DEBUG
 namespace {
 
 bool CanSubclassHaveInobjectProperties(InstanceType instance_type) {
   switch (instance_type) {
     case JS_API_OBJECT_TYPE:
     case JS_ARRAY_BUFFER_TYPE:
     case JS_ARRAY_TYPE:
+    case JS_ASYNC_FROM_SYNC_ITERATOR_TYPE:
     case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
     case JS_DATA_VIEW_TYPE:
     case JS_DATE_TYPE:
     case JS_FUNCTION_TYPE:
     case JS_GENERATOR_OBJECT_TYPE:
     case JS_MAP_ITERATOR_TYPE:
     case JS_MAP_TYPE:
     case JS_MESSAGE_OBJECT_TYPE:
     case JS_OBJECT_TYPE:
     case JS_ERROR_TYPE:
@@ skipping 7553 matching lines @@
       // depend on this.
       return DICTIONARY_ELEMENTS;
     }
     DCHECK_LE(kind, LAST_ELEMENTS_KIND);
     return kind;
   }
 }
 
 }  // namespace internal
 }  // namespace v8