Make isEmpty a getter.

lib/core/future.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 [Future] is used to obtain a value sometime in the future.  Receivers of a
  * [Future] can obtain the value by passing a callback to [then]. For example:
  *
  *     Future<int> future = getFutureFromSomewhere();
  *     future.then((value) {
@@ skipping 210 matching lines @@
  * example, waiting for a collection of Futures to complete).
  */
 class Futures {
   /**
    * Returns a future which will complete once all the futures in a list are
    * complete. If any of the futures in the list completes with an exception,
    * the resulting future also completes with an exception. (The value of the
    * returned future will be a list of all the values that were produced.)
    */
   static Future<List> wait(List<Future> futures) {
-    if (futures.isEmpty()) {
+    if (futures.isEmpty) {
       return new Future<List>.immediate(const []);
     }
 
     Completer completer = new Completer<List>();
     Future<List> result = completer.future;
     int remaining = futures.length;
     List values = new List(futures.length);
 
     // As each future completes, put its value into the corresponding
     // position in the list of values.
@@ skipping 11 matching lines @@
       future.handleException((exception) {
         if (!result.isComplete) {
           completer.completeException(exception, future.stackTrace);
         }
         return true;
       });
     }
     return result;
   }
 }