Fix type annotation issue.

tests/isolate/mint_maker_test.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.
 
 // Things that should be "auto-generated" are between AUTO START and
 // AUTO END (or just AUTO if it's a single line).
 
 #library("MintMakerTest");
 #import("dart:isolate");
 #import('../../lib/unittest/unittest.dart');
@@ skipping 163 matching lines @@
     port_ = spawnFunction(mintMakerWrapper);
   }
 
   void makeMint(handleMint(MintWrapper mint)) {
     port_.call(null).then((var message) {
       SendPort mint = message[0];
       handleMint(new MintWrapper(mint));
     });
   }
 
-  Future<SendPort> port_;
+  SendPort port_;
 }
 
 _checkBalance(PurseWrapper wrapper, expected) {
   wrapper.queryBalance(expectAsync1((int balance) {
     expect(balance, equals(expected));
   }));
 }
 
 main() {
   test("creating purse, deposit, and query balance", () {
@@ skipping 57 matching lines @@
     sprouted...deposit(purse, 5);
     Expect.equals(0 + 5, sprouted.queryBalance());
     Expect.equals(100 - 5, purse.queryBalance());
 
     sprouted...deposit(purse, 42);
     Expect.equals(0 + 5 + 42, sprouted.queryBalance());
     Expect.equals(100 - 5 - 42, purse.queryBalance());
   }
   */
 }