Support language tag extensions with multiple subtags for a key

test/intl/date-format/calendar-with-multiple-type-subtags.js

Index: test/intl/date-format/calendar-with-multiple-type-subtags.js
diff --git a/test/intl/date-format/calendar-with-multiple-type-subtags.js b/test/intl/date-format/calendar-with-multiple-type-subtags.js
new file mode 100644
index 0000000000000000000000000000000000000000..f4c00da61d3ab230dff6b51247d40243926fdfe2
--- /dev/null
+++ b/test/intl/date-format/calendar-with-multiple-type-subtags.js
@@ -0,0 +1,39 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+var options = Intl.DateTimeFormat("ar-u-ca-islamic-civil").resolvedOptions();
+assertEquals(options.calendar, "islamic-civil");
+
+options = Intl.DateTimeFormat("ar-u-ca-islamic-umalqura").resolvedOptions();
+assertEquals(options.calendar, "islamic-umalqura");
+
+var options = Intl.DateTimeFormat("ar-u-ca-islamic-civil").resolvedOptions();
+assertEquals(options.calendar, "islamic-civil");
+
+options =
+    Intl.DateTimeFormat("ar-u-ca-islamic-civil-nu-arab").resolvedOptions();
+assertEquals(options.calendar, "islamic-civil");
+assertEquals(options.numberingSystem, "arab");
+
+// The default numberingSystem is 'arab' for 'ar' locale. Set it to 'latn'
+// to check that 'nu-latn' keyword is parsed correctly.
+options =
+    Intl.DateTimeFormat("ar-u-ca-islamic-civil-nu-latn").resolvedOptions();
+assertEquals(options.calendar, "islamic-civil");
+assertEquals(options.numberingSystem, "latn");
+
+// ethioaa is the canonical LDML/BCP 47 name.
+options = Intl.DateTimeFormat("am-u-ca-ethiopic-amete-alem").resolvedOptions();
+assertEquals(options.calendar, "ethioaa");
+
+// Invalid calendar type "foo-bar". Fall back to the default.
+options = Intl.DateTimeFormat("ar-u-ca-foo-bar").resolvedOptions();
+assertEquals(options.calendar, "gregory");
+
+// No type subtag for ca. Fall back to the default.
+options = Intl.DateTimeFormat("ar-u-ca-nu-arab").resolvedOptions();
+assertEquals(options.calendar, "gregory");
+
+// Too long a type subtag for ca.
+assertThrows(() => Intl.DateTimeFormat("ar-u-ca-foobarbaz"), RangeError);