Improve i18n date/time test performance

pkg/i18n/lib/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.
 
 /**
  * A class for holding onto the data for a date so that it can be built
  * up incrementally.
  */
 class _DateBuilder {
   int year = 0,
@@ skipping 107 matching lines @@
     while (!atEnd()) {
       if (f(next())) results.add(index - 1);
     }
     return results;
   }
 
   /**
    * Assuming that the contents are characters, read as many digits as we
    * can see and then return the corresponding integer. Advance the stream.
    */
+  var digitMatcher = const RegExp(@'\d');
   int nextInteger() {
-    var validDigits = '0123456789';
+    // Doing this with a regular expression is slightly slower on the VM,
+    // but makes a moderate difference in Javascript right now.

[Emily Fortuna, 2012/08/18 00:46:30]

perhaps we could do something a little fancier like find the first non-digit
character using a regular expression, and parse that set of digit charaters
together, so we're not always going digit by digit.

     var digits = [];
-    while (!atEnd() && (validDigits.contains(peek()))) {
+    while (!atEnd() && (digitMatcher.hasMatch(peek()))) {
       digits.add(next().charCodeAt(0));
     }
     return Math.parseInt(new String.fromCharCodes(digits));
   }
 }