Tighten up a couple method signatures to specify that int is required.

lib/src/intl/date_format_helpers.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.
 
 
 part of intl;
 
 /**
  * A class for holding onto the data for a date so that it can be built
  * up incrementally.
@@ skipping 106 matching lines @@
   _Stream(this.contents);
 
   bool atEnd() => index >= contents.length;
 
   next() => contents[index++];
 
   /**
    * Return the next [howMany] items, or as many as there are remaining.
    * Advance the stream by that many positions.
    */
-  read([howMany = 1]) {
+  read([int howMany = 1]) {
     var result = peek(howMany);
     index += howMany;
     return result;
   }
 
   /**
    * Does the input start with the given string, if we start from the
    * current position.
    */
   bool startsWith(String pattern) {
     if (contents is String) return contents.startsWith(pattern, index);
     return pattern == peek(pattern.length);
   }
 
   /**
    * Return the next [howMany] items, or as many as there are remaining.
    * Does not modify the stream position.
    */
-  peek([howMany = 1]) {
+  peek([int howMany = 1]) {
     var result;
     if (contents is String) {
       result = contents.substring(
           index,
           min(index + howMany, contents.length));
     } else {
       // Assume List
       result = contents.sublist(index, index + howMany);
     }
     return result;
@@ skipping 30 matching lines @@
    * can see and then return the corresponding integer. Advance the stream.
    */
   var digitMatcher = new RegExp(r'\d+');
   int nextInteger() {
     var string = digitMatcher.stringMatch(rest());
     if (string == null || string.isEmpty) return null;
     read(string.length);
     return int.parse(string);
   }
 }