Also mark as prototype when passing in while creating a function.

BUG=
R=ishell@chromium.org

Review URL: https://codereview.chromium.org/422233010

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22830 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/factory.cc

@@ -1268,6 +1268,11 @@ Handle<JSFunction> Factory::NewFunction(Handle<String> name,
       ? isolate()->sloppy_function_with_readonly_prototype_map()
       : isolate()->sloppy_function_map();
   Handle<JSFunction> result = NewFunction(map, name, code);
+  if (!prototype->IsTheHole()) {
+    Handle<JSObject> js_proto = Handle<JSObject>::cast(prototype);
+    Handle<Map> new_map = Map::CopyAsPrototypeMap(handle(js_proto->map()));
+    JSObject::MigrateToMap(js_proto, new_map);
+  }
   result->set_prototype_or_initial_map(*prototype);
   return result;
 }

src/objects.cc

@@ -7288,6 +7288,7 @@ Handle<Map> Map::CopyForObserved(Handle<Map> map) {
 
 
 Handle<Map> Map::CopyAsPrototypeMap(Handle<Map> map) {
+  if (map->is_prototype_map()) return map;
   Handle<Map> result = Copy(map);
   result->mark_prototype_map();
   return result;