Make sure to always remove temp directory.

tests/standalone/io/file_input_stream_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.
 // Testing file input stream, VM-only, standalone test.
 
 import "dart:convert";
 import "dart:io";
 
 import "package:async_helper/async_helper.dart";
 import "package:expect/expect.dart";
@@ skipping 196 matching lines @@
     asyncStart();
     var temp = Directory.systemTemp.createTempSync('file_input_stream_test');
     var file = new File('${temp.path}/input_stream_bad_offset.txt');
     var originalLength = writeLongFileSync(file);
     var streamedBytes = 0;
     file.openRead(start, end).listen(
         (d) {
           streamedBytes += d.length;
         },
         onDone: () {
-          temp.delete(recursive: true);
+          if (temp.existsSync()) {
+            temp.delete(recursive: true);

[Søren Gjesse, 2014/04/10 14:27:59]

Use deleteSync

+          }
         },
         onError: (e) {
+          if (temp.existsSync()) {
+            temp.delete(recursive: true);

[Søren Gjesse, 2014/04/10 14:27:59]

Use deleteSync or call asyncEnd in the Future returned by delete.

+          }
           asyncEnd();
         });
   }
   test(-1, null);
   test(100, 99);
   test(null, -1);
 }
 
 
 void testStringLineSplitterEnding(String name, int length) {
@@ skipping 26 matching lines @@
   testInputStreamDelete();
   testInputStreamAppend();
   testInputStreamOffset();
   testInputStreamBadOffset();
   // Check the length of these files as both are text files where one
   // is without a terminating line separator which can easily be added
   // back if accidentally opened in a text editor.
   testStringLineSplitterEnding("readline_test1.dat", 111);
   testStringLineSplitterEnding("readline_test2.dat", 114);
 }