Async initialization for DateFormat

pkg/intl/data/dates/symbols/nl.json

Index: pkg/intl/data/dates/symbols/nl.json
===================================================================
--- pkg/intl/data/dates/symbols/nl.json	(revision 0)
+++ pkg/intl/data/dates/symbols/nl.json	(revision 0)
@@ -0,0 +1 @@
+{"DATEFORMATS":["EEEE d MMMM y","d MMMM y","d MMM y","dd-MM-yy"],"NARROWWEEKDAYS":["Z","M","D","W","D","V","Z"],"STANDALONESHORTMONTHS":["jan","feb","mrt","apr","mei","jun","jul","aug","sep","okt","nov","dec"],"ERANAMES":["Voor Christus","na Christus"],"FIRSTWEEKCUTOFFDAY":3,"NARROWMONTHS":["J","F","M","A","M","J","J","A","S","O","N","D"],"STANDALONESHORTWEEKDAYS":["zo","ma","di","wo","do","vr","za"],"FIRSTDAYOFWEEK":0,"STANDALONEWEEKDAYS":["zondag","maandag","dinsdag","woensdag","donderdag","vrijdag","zaterdag"],"WEEKDAYS":["zondag","maandag","dinsdag","woensdag","donderdag","vrijdag","zaterdag"],"QUARTERS":["1e kwartaal","2e kwartaal","3e kwartaal","4e kwartaal"],"ERAS":["v. Chr.","n. Chr."],"MONTHS":["januari","februari","maart","april","mei","juni","juli","augustus","september","oktober","november","december"],"TIMEFORMATS":["HH:mm:ss zzzz","HH:mm:ss z","HH:mm:ss","HH:mm"],"SHORTWEEKDAYS":["zo","ma","di","wo","do","vr","za"],"SHORTQUARTERS":["K1","K2","K3","K4"],"WEEKENDRANGE":[5,6],"STANDALONENARROWWEEKDAYS":["Z","M","D","W","D","V","Z"],"AVAILABLEFORMATS":null,"NAME":"nl","AMPMS":["AM","PM"],"STANDALONEMONTHS":["januari","februari","maart","april","mei","juni","juli","augustus","september","oktober","november","december"],"SHORTMONTHS":["jan.","feb.","mrt.","apr.","mei","jun.","jul.","aug.","sep.","okt.","nov.","dec."],"STANDALONENARROWMONTHS":["J","F","M","A","M","J","J","A","S","O","N","D"]}