set an undefined __proto__ if function_prototype doesn't exist
set an undefined __proto__ if function_prototype doesn't exist

Fixes Flash 5 problems

mltframework/swfdec,freedesktop-unofficial-mirror/swfdec__swfdec,freedesktop-unofficial-mirror/swfdec__swfdec,freedesktop-unofficial-mirror/swfdec__swfdec,mltframework/swfdec