arrange to create prototypes for generators

src/factory.cc

Index: src/factory.cc
diff --git a/src/factory.cc b/src/factory.cc
index fece9a09c91779c6f360d842a7c2b3b9a7a51791..2c0ceb192c9edfbb724f3067e8dda04a9ed0c85e 100644
--- a/src/factory.cc
+++ b/src/factory.cc
@@ -578,15 +578,22 @@ Handle<JSFunction> Factory::BaseNewFunctionFromSharedFunctionInfo(
 }
 
 
+static Handle<Map> MapForNewFunction(Isolate *isolate,
+                                     Handle<SharedFunctionInfo> function_info) {
+  Context *context = isolate->context()->native_context();
+  int map_index = Context::FunctionMapIndex(function_info->language_mode(),
+                                            function_info->is_generator());
+  return Handle<Map>(Map::cast(context->get(map_index)));
+}
+
+
 Handle<JSFunction> Factory::NewFunctionFromSharedFunctionInfo(
     Handle<SharedFunctionInfo> function_info,
     Handle<Context> context,
     PretenureFlag pretenure) {
   Handle<JSFunction> result = BaseNewFunctionFromSharedFunctionInfo(
       function_info,
-      function_info->is_classic_mode()
-          ? isolate()->function_map()
-          : isolate()->strict_mode_function_map(),
+      MapForNewFunction(isolate(), function_info),
       pretenure);
 
   if (function_info->ic_age() != isolate()->heap()->global_ic_age()) {