Modify tests to use Directory.systemTemp

tests/standalone/io/dart_std_io_pipe_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.
 //
 // Test a dart sub-process handling stdio with different types of
 // redirection.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
@@ skipping 14 matching lines @@
   RandomAccessFile pipeOut  = new File(fileName).openSync();
   int length = pipeOut.lengthSync();
   List data = new List<int>(length);
   pipeOut.readIntoSync(data, 0, length);
   Expect.equals(content, new String.fromCharCodes(data));
   pipeOut.closeSync();
 }
 
 
 void test(String shellScript, String dartScript, String type, bool devNull) {
-  Directory dir = new Directory("").createTempSync();
+  Directory dir = Directory.systemTemp.createTempSync('dart_dart_std_io_pipe');
 
   // The shell script will run the dart executable passed with a
   // number of different redirections of stdio.
   String pipeOutFile = "${dir.path}/pipe";
   if (devNull) pipeOutFile = "/dev/null";
   String redirectOutFile = "${dir.path}/redirect";
   String executable = Platform.executable;
   List args =
       [executable,
        dartScript,
@@ skipping 72 matching lines @@
   }
 
   // Run the shell script.
   test(shellScript.path, scriptFile.path, "0", false);
   test(shellScript.path, scriptFile.path, "0", true);
   test(shellScript.path, scriptFile.path, "1", false);
   test(shellScript.path, scriptFile.path, "1", true);
   test(shellScript.path, scriptFile.path, "2", false);
   test(shellScript.path, scriptFile.path, "2", true);
 }