[promises] PromiseResolveThenableJob: change then to be a JSReceiver

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/isolate.h"
 #include "src/messages.h"
 #include "src/type-feedback-vector.h"
@@ skipping 44 matching lines @@
                                    PretenureFlag pretenure = NOT_TENURED);
 
   Handle<OrderedHashSet> NewOrderedHashSet();
   Handle<OrderedHashMap> NewOrderedHashMap();
 
   // Create a new boxed value.
   Handle<Box> NewBox(Handle<Object> value);
 
   // Create a new PromiseContainer struct.
   Handle<PromiseContainer> NewPromiseContainer(
-      Handle<JSReceiver> thenable, Handle<JSFunction> then,
+      Handle<JSReceiver> thenable, Handle<JSReceiver> then,
       Handle<JSFunction> resolve, Handle<JSFunction> reject,
       Handle<Object> before_debug_event, Handle<Object> after_debug_event);
 
   // Create a new PrototypeInfo struct.
   Handle<PrototypeInfo> NewPrototypeInfo();
 
   // Create a new ContextExtension struct.
   Handle<ContextExtension> NewContextExtension(Handle<ScopeInfo> scope_info,
                                                Handle<Object> extension);
 
@@ skipping 696 matching lines @@
                                      FunctionMode function_mode);
 
   void SetStrictFunctionInstanceDescriptor(Handle<Map> map,
                                            FunctionMode function_mode);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_FACTORY_H_