[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 98ffb2b1bd47e8c177aac841ffd0a27749297240..50d0137fa025caef9443b045faa427d5e2c98e3e 100644
--- a/src/factory.h
+++ b/src/factory.h
@@ -558,6 +558,8 @@ 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<JSReceiver> sync_iterator);
 
   Handle<JSMap> NewJSMap();
   Handle<JSSet> NewJSSet();