Async initialization for DateFormat

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

Index: pkg/intl/data/dates/symbols/cs.json
===================================================================
--- pkg/intl/data/dates/symbols/cs.json	(revision 0)
+++ pkg/intl/data/dates/symbols/cs.json	(revision 0)
@@ -0,0 +1 @@
+{"DATEFORMATS":["EEEE, d. MMMM y","d. MMMM y","d. M. yyyy","dd.MM.yy"],"NARROWWEEKDAYS":["N","P","Ú","S","Č","P","S"],"STANDALONESHORTMONTHS":["1.","2.","3.","4.","5.","6.","7.","8.","9.","10.","11.","12."],"ERANAMES":["př. n. l.","n. l."],"FIRSTWEEKCUTOFFDAY":3,"NARROWMONTHS":["1","2","3","4","5","6","7","8","9","10","11","12"],"STANDALONESHORTWEEKDAYS":["ne","po","út","st","čt","pá","so"],"FIRSTDAYOFWEEK":0,"STANDALONEWEEKDAYS":["neděle","pondělí","úterý","středa","čtvrtek","pátek","sobota"],"WEEKDAYS":["neděle","pondělí","úterý","středa","čtvrtek","pátek","sobota"],"QUARTERS":["1. čtvrtletí","2. čtvrtletí","3. čtvrtletí","4. čtvrtletí"],"ERAS":["př. n. l.","n. l."],"MONTHS":["ledna","února","března","dubna","května","června","července","srpna","září","října","listopadu","prosince"],"TIMEFORMATS":["H:mm:ss zzzz","H:mm:ss z","H:mm:ss","H:mm"],"SHORTWEEKDAYS":["ne","po","út","st","čt","pá","so"],"SHORTQUARTERS":["Q1","Q2","Q3","Q4"],"WEEKENDRANGE":[5,6],"STANDALONENARROWWEEKDAYS":["N","P","Ú","S","Č","P","S"],"AVAILABLEFORMATS":null,"NAME":"cs","AMPMS":["dop.","odp."],"STANDALONEMONTHS":["leden","únor","březen","duben","květen","červen","červenec","srpen","září","říjen","listopad","prosinec"],"SHORTMONTHS":["Led","Úno","Bře","Dub","Kvě","Čer","Čvc","Srp","Zář","Říj","Lis","Pro"],"STANDALONENARROWMONTHS":["l","ú","b","d","k","č","č","s","z","ř","l","p"]}