Consider :before and :after outline and shadow

Sometimes pseudo element could have `box-shadow` larger than its parent. In this case screenshot would not capture its shadow. Example here (moved `box-shadow` from element to `:before`): http://nda.ya.ru/3QTQuu
There is no way to capture pseudo-elements by selector, so maybe we could take `:before` and `:after` into account while calculating element rectangle?