Update dart:io tests to use asyncStart/asyncEnd

tests/standalone/io/file_fuzz_test.dart

 // Copyright (c) 2013, 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.
 
 // 'fuzz' test the file APIs by providing unexpected type arguments. The test
 // passes if the VM does not crash.
 
 import 'dart:async';
 import 'dart:io';
-import 'dart:isolate';
 
 import 'fuzz_support.dart';
 
+import "package:async_helper/async_helper.dart";
+
 fuzzSyncMethods() {
   typeMapping.forEach((k, v) {
     doItSync(() {
       var f = new File(v);
       doItSync(f.existsSync);
       doItSync(f.createSync);
       doItSync(f.deleteSync);
       doItSync(f.lengthSync);
       doItSync(f.modifiedSync);
       doItSync(f.fullPathSync);
       doItSync(() => f.openRead().listen((_) {}, onError: (e) {}));
       doItSync(f.readAsBytesSync);
       doItSync(f.readAsStringSync);
       doItSync(f.readAsLinesSync);
       typeMapping.forEach((k2, v2) {
         doItSync(() => f.openSync(mode: v2));
         doItSync(() => f.openWrite(mode: v2));
         doItSync(() => f.readAsStringSync(encoding: v2));
         doItSync(() => f.readAsLinesSync(encoding: v2));
       });
     });
   });
 }
 
 fuzzAsyncMethods() {
-  var port = new ReceivePort();
+  asyncStart();
   var futures = [];
   typeMapping.forEach((k, v) {
     doItSync(() {
       var f = new File(v);
       futures.add(doItAsync(f.exists));
       futures.add(doItAsync(f.delete));
       futures.add(doItAsync(f.directory));
       futures.add(doItAsync(f.length));
       futures.add(doItAsync(f.modified));
       futures.add(doItAsync(f.open));
       futures.add(doItAsync(f.fullPath));
       futures.add(doItAsync(f.readAsBytes));
       futures.add(doItAsync(f.readAsLines));
       futures.add(doItAsync(f.readAsString));
       typeMapping.forEach((k2, v2) {
         futures.add(doItAsync(() => f.open(mode: v2)));
         futures.add(doItAsync(() => f.readAsString(encoding: v2)));
         futures.add(doItAsync(() => f.readAsLines(encoding: v2)));
       });
     });
   });
-  Future.wait(futures).then((ignore) => port.close());
+  Future.wait(futures).then((_) => asyncEnd());
 }
 
 
 fuzzSyncRandomAccessMethods() {
   var d = new Directory('');
   var temp = d.createTempSync();
   var file = new File('${temp.path}/x');
   file.createSync();
   var modes = [ FileMode.READ, FileMode.WRITE, FileMode.APPEND ];
   for (var m in modes) {
@@ skipping 46 matching lines @@
     temp.deleteSync(recursive: true);
   });
 }
 
 main() {
   fuzzSyncMethods();
   fuzzAsyncMethods();
   fuzzSyncRandomAccessMethods();
   fuzzAsyncRandomAccessMethods();
 }