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

src/factory.h

Index: src/factory.h
diff --git a/src/factory.h b/src/factory.h
index 5a7d36fbfad22efe5e86497608b6cbe3e44c5136..45dfa2dc37e219d6bed6e01dd53170cd9e26eea5 100644
--- a/src/factory.h
+++ b/src/factory.h
@@ -561,6 +561,8 @@ class V8_EXPORT_PRIVATE Factory final {
                                    size_t byte_offset, size_t byte_length);
 
   Handle<JSIteratorResult> NewJSIteratorResult(Handle<Object> value, bool done);
+  Handle<JSAsyncFromSyncIterator> NewJSAsyncFromSyncIterator(
+      Handle<HeapObject> sync_iterator);
 
   Handle<JSMap> NewJSMap();
   Handle<JSSet> NewJSSet();