Allow multiple patterns for date formats

pkg/intl/test/date_time_format_test.dart

 /**
  * Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
  * for details. All rights reserved. Use of this source code is governed by a
  * BSD-style license that can be found in the LICENSE file.
  */
 
 #library('date_time_format_test');
 
 #import('../intl.dart');
 #import('../date_format.dart');
@@ skipping 151 matching lines @@
       var format = new DateFormat(skeleton, localeName);
       var actualResult = format.format(date);
       var parsed = format.parse(actualResult);
       var thenPrintAgain = format.format(parsed);
       expect(thenPrintAgain, equals(actualResult));
     }
   }
 }
 
 main() {
+  test('Multiple patterns', () {
+    var date = new Date.now();
+    var multiple1 = new DateFormat.yMd().jms();
+    var multiple2 = new DateFormat("yMd").jms();
+    var separate1 = new DateFormat.yMd();
+    var separate2 = new DateFormat.jms();
+    var separateFormat = "${separate1.format(date)} ${separate2.format(date)}";
+    expect(multiple1.format(date), equals(multiple2.format(date)));
+    expect(multiple1.format(date), equals(separateFormat));
+    var customPunctuation = new DateFormat("yMd").addPattern("jms",":::");
+    var custom = "${separate1.format(date)}:::${separate2.format(date)}";
+    expect(customPunctuation.format(date), equals(custom));
+  });
+
   test('Basic date format parsing', () {
     var date_format = new DateFormat("d");
     expect(
         date_format.parsePattern("hh:mm:ss").map((x) => x.pattern),
         orderedEquals(["hh",":", "mm",":","ss"]));
     expect(
         date_format.parsePattern("hh:mm:ss").map((x) => x.pattern),
         orderedEquals(["hh",":", "mm",":","ss"]));
   });
 
@@ skipping 103 matching lines @@
     var localPrinted = format.format(local);
     var parsed = format.parse(localPrinted);
     var parsedUTC = format.parseUTC(format.format(utc));
     var parsedOffset = parsedUTC.millisecondsSinceEpoch
         - parsed.millisecondsSinceEpoch;
     expect(parsedOffset, equals(offset));
     expect(utc.hour, equals(parsedUTC.hour));
     expect(local.hour, equals(parsed.hour));
     });
 }