Add phonetic name as one of ContactAddress properties #70

Apple recently decided to add support for phonetic name in its Payment Request API's PaymentAddress object.

In Japan, people use 3 different characters - Kanji, Hiragana and Katakana. Texts are usually written in mixture of those 3 characters. While Kanji is written for content words, Hiragana and Katakana (they are equivalent different shapes) are written for phonetics. Names written in Kanji needs accompanying Hiragana or Katakana in order to be pronounced properly. That's where phonetic name field helps. They exists commonly in checkout forms in Japanese ecommerce services.

Therefore, I would like to propose to add DOMString phoneticName as a member of PaymentAddress object.