Make isEmpty a getter.

pkg/intl/lib/src/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 {
   // Default the date values to the EPOCH so that there's a valid date
@@ skipping 115 matching lines @@
     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(r'\d+');
   int nextInteger() {
     var string = digitMatcher.stringMatch(rest());
-    if (string == null || string.isEmpty()) return null;
+    if (string == null || string.isEmpty) return null;
     read(string.length);
     return int.parse(string);
   }
 }