Bug 1543644: Include RBNF data for Japanese to support Gannen year re…

…presentation. r=jwalden

ICU changes the numbering system of date formats which include an era marker
to "jpanyear". "jpanyear" is a rule-based numbering system and therefore the
RBNF data for the Japanese locale now need to be included.

Differential Revision: https://phabricator.services.mozilla.com/D27340

intl/icu/data_filter.json

@@ -19,7 +19,8 @@
             "filterType": "exclude"
         },
         "rbnf_tree": {
-            "filterType": "exclude"
+            "filterType": "locale",
+            "whitelist": [ "ja" ]
         },
         "region_tree": {
             "filterType": "exclude"

js/src/tests/non262/Intl/DateTimeFormat/japanese-gannen-year.js

@@ -0,0 +1,29 @@
+// |reftest| skip-if(!this.hasOwnProperty("Intl"))
+
+var dtf = new Intl.DateTimeFormat("ja-u-ca-japanese", {
+    era: "short",
+    timeZone: "Asia/Tokyo",
+});
+
+var endShowa = new Date("1989-01-07T00:00:00.000Z");
+var startHeisei = new Date("1989-01-08T00:00:00.000Z");
+
+assertEq(dtf.format(endShowa), "昭和64年1月7日");
+assertEq(dtf.format(startHeisei), "平成元年1月8日");
+
+var parts = dtf.formatToParts(startHeisei);
+assertEq(parts.filter(p => p.type === "era")[0].value, "平成");
+assertEq(parts.filter(p => p.type === "year")[0].value, "元");
+
+// ICU returns mixed numbers when an explicit numbering system is present.
+
+var dtf = new Intl.DateTimeFormat("ja-u-ca-japanese-nu-arab", {
+    era: "short",
+    timeZone: "Asia/Tokyo",
+});
+
+assertEq(dtf.format(endShowa), "昭和64年١月٧日");
+assertEq(dtf.format(startHeisei), "平成元年١月٨日");
+
+if (typeof reportCompare === "function")
+    reportCompare(0, 0);