Make isEmpty a getter.

lib/core/string.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.
 
 /**
  * The String class represents character strings. Strings are
  * immutable. A string is represented by a list of 32-bit Unicode
  * scalar character codes accessible through the [charCodeAt] or the
  * [charCodes] method.
  */
@@ skipping 46 matching lines @@
   /**
    * Returns the last location of [other] in this string, searching
    * backward starting at [start] (inclusive).
    * Returns -1 if [other] could not be found.
    */
   int lastIndexOf(String other, [int start]);
 
   /**
    * Returns whether this string is empty.
    */
-  bool isEmpty();
+  bool get isEmpty;
 
   /**
    * Creates a new string by concatenating this string with [other].
    */
   String concat(String other);
 
   /**
    * Returns a substring of this string in the given range.
    * [startIndex] is inclusive and [endIndex] is exclusive.
    */
@@ skipping 46 matching lines @@
    * where all characters  are made lower case. Returns [:this:] otherwise.
    */
   String toLowerCase();
 
   /**
    * If this string is not already all uper case, returns a new string
    * where all characters are made upper case. Returns [:this:] otherwise.
    */
   String toUpperCase();
 }