Generator objects have [[Class]] === "Generator"

src/factory.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 436 matching lines @@
   INTERNALIZED_STRING_LIST(STRING_ACCESSOR)
 #undef STRING_ACCESSOR
 
   Handle<String> hidden_string() {
     return Handle<String>(&isolate()->heap()->hidden_string_);
   }
 
   Handle<SharedFunctionInfo> NewSharedFunctionInfo(
       Handle<String> name,
       int number_of_literals,
+      bool is_generator,
       Handle<Code> code,
       Handle<ScopeInfo> scope_info);
   Handle<SharedFunctionInfo> NewSharedFunctionInfo(Handle<String> name);
 
   Handle<JSMessageObject> NewJSMessageObject(
       Handle<String> type,
       Handle<JSArray> arguments,
       int start_position,
       int end_position,
       Handle<Object> script,
@@ skipping 59 matching lines @@
   // Update the map cache in the native context with (keys, map)
   Handle<MapCache> AddToMapCache(Handle<Context> context,
                                  Handle<FixedArray> keys,
                                  Handle<Map> map);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_FACTORY_H_