Add PluralRules interface (#3176)
Add PluralRules interface (#3176)

* Add PluralRules interface.

* Update javascript/builtins/PluralRules.json

Co-Authored-By: jpmedley <e5f32d9ca37888f2e401c8370536acae62d3b209@google.com>

* Fix missing data.

mdn/browser-compat-data,chrisdavidmills/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data