WIP [esnext] implement async iteration proposal

src/factory.h

 // Copyright 2014 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.
 
 #ifndef V8_FACTORY_H_
 #define V8_FACTORY_H_
 
 #include "src/globals.h"
 #include "src/isolate.h"
 #include "src/messages.h"
@@ skipping 515 matching lines @@
   // Creates a new on-heap JSTypedArray.
   Handle<JSTypedArray> NewJSTypedArray(ElementsKind elements_kind,
                                        size_t number_of_elements,
                                        PretenureFlag pretenure = NOT_TENURED);
 
   Handle<JSDataView> NewJSDataView();
   Handle<JSDataView> NewJSDataView(Handle<JSArrayBuffer> buffer,
                                    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();
 
   // TODO(aandrey): Maybe these should take table, index and kind arguments.
   Handle<JSMapIterator> NewJSMapIterator();
   Handle<JSSetIterator> NewJSSetIterator();
 
   // Allocates a bound function.
   MaybeHandle<JSBoundFunction> NewJSBoundFunction(
@@ skipping 256 matching lines @@
   void SetStrictFunctionInstanceDescriptor(Handle<Map> map,
                                            FunctionMode function_mode);
 
   void SetClassFunctionInstanceDescriptor(Handle<Map> map);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_FACTORY_H_