Fix tests in language suite: eliminate String +

runtime/lib/date.dart

 // Copyright (c) 2011, 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.
 // Dart core library.
 
 class TimeZoneImplementation implements TimeZone {
   const TimeZoneImplementation.utc() : isUtc = true;
   TimeZoneImplementation.local() : isUtc = false {}
 
   bool operator ==(Object other) {
@@ skipping 43 matching lines @@
     // Read in (a subset of) ISO 8601.
     // Examples:
     //    - "2012-02-27 13:27:00"
     //    - "2012-02-27 13:27:00.423z"
     //    - "20120227 13:27:00"
     //    - "20120227T132700"
     //    - "20120227"
     //    - "2012-02-27T14Z"
     //    - "-123450101 00:00:00 Z"  // In the year -12345.
     final RegExp re = const RegExp(
-        @'^([+-]?\d?\d\d\d\d)-?(\d\d)-?(\d\d)' +  // The day part.
+        @'^([+-]?\d?\d\d\d\d)-?(\d\d)-?(\d\d)'  // The day part.
         @'(?:[ T](\d\d)(?::?(\d\d)(?::?(\d\d)(.\d{1,6})?)?)? ?([zZ])?)?$');
     Match match = re.firstMatch(formattedString);
     if (match !== null) {
       int parseIntOrZero(String matched) {
         // TODO(floitsch): we should not need to test against the empty string.
         if (matched === null || matched == "") return 0;
         return Math.parseInt(matched);
       }
 
       double parseDoubleOrZero(String matched) {
@@ skipping 339 matching lines @@
 
   static int _getHours(int secondsSinceEpoch, bool isUtc)
       native "DateNatives_getHours";
 
   static int _getMinutes(int secondsSinceEpoch, bool isUtc)
       native "DateNatives_getMinutes";
 
   static int _getSeconds(int secondsSinceEpoch, bool isUtc)
       native "DateNatives_getSeconds";
 }