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

src/factory.cc

 // 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 1060 matching lines @@
 void Factory::SetIdentityHash(Handle<JSObject> object, Smi* hash) {
   CALL_HEAP_FUNCTION_VOID(
       isolate(),
       object->SetIdentityHash(hash, ALLOW_CREATION));
 }
 
 
 Handle<SharedFunctionInfo> Factory::NewSharedFunctionInfo(
     Handle<String> name,
     int number_of_literals,
+    bool is_generator,
     Handle<Code> code,
     Handle<ScopeInfo> scope_info) {
   Handle<SharedFunctionInfo> shared = NewSharedFunctionInfo(name);
   shared->set_code(*code);
   shared->set_scope_info(*scope_info);
   int literals_array_size = number_of_literals;
   // If the function contains object, regexp or array literals,
   // allocate extra space for a literals array prefix containing the
   // context.
   if (number_of_literals > 0) {
     literals_array_size += JSFunction::kLiteralsPrefixSize;
   }
   shared->set_num_literals(literals_array_size);
+  if (is_generator) {
+    shared->set_instance_class_name(isolate()->heap()->Generator_string());
+  }
   return shared;
 }
 
 
 Handle<JSMessageObject> Factory::NewJSMessageObject(
     Handle<String> type,
     Handle<JSArray> arguments,
     int start_position,
     int end_position,
     Handle<Object> script,
@@ skipping 375 matching lines @@
   return Handle<Object>::null();
 }
 
 
 Handle<Object> Factory::ToBoolean(bool value) {
   return value ? true_value() : false_value();
 }
 
 
 } }  // namespace v8::internal