punycode.decode only accept ASCII-only input
punycode.decode only accept ASCII-only input

fix #6540

Auditors: @diracdeltas

Test Plan:
1. Go to http://xn--jp%29-5y3b.f1-live.com/f1/jp/headlines/news/detail/060912193351.shtml
2. There should be a DNS error page

luixxiul/browser-laptop,darkdh/browser-laptop,diasdavid/browser-laptop,luixxiul/browser-laptop,luixxiul/browser-laptop,diasdavid/browser-laptop,timborden/browser-laptop,timborden/browser-laptop,luixxiul/browser-laptop,diasdavid/browser-laptop,diasdavid/browser-laptop,darkdh/browser-laptop,timborden/browser-laptop,darkdh/browser-laptop,timborden/browser-laptop,darkdh/browser-laptop