Modify tests to use Directory.systemTemp

tests/standalone/io/directory_non_ascii_sync_test.dart

Index: tests/standalone/io/directory_non_ascii_sync_test.dart
diff --git a/tests/standalone/io/directory_non_ascii_sync_test.dart b/tests/standalone/io/directory_non_ascii_sync_test.dart
index f73225f72c0a3bf097b74f724cf80ed442e26644..68eafef73d0eec77d0cb1710d0ba2ea857e3f386 100644
--- a/tests/standalone/io/directory_non_ascii_sync_test.dart
+++ b/tests/standalone/io/directory_non_ascii_sync_test.dart
@@ -6,7 +6,8 @@ import "package:expect/expect.dart";
 import 'dart:io';
 
 main() {
-  Directory tempDir = new Directory('').createTempSync();
+  Directory tempDir =
+      Directory.systemTemp.createTempSync('dart_directory_non_ascii_sync');
   var nonAsciiDir = new Directory("${tempDir.path}/æøå");
   // On MacOS you get the decomposed utf8 form of file and directory
   // names from the system. Therefore, we have to check for both here.
@@ -15,7 +16,11 @@ main() {
   Expect.isFalse(nonAsciiDir.existsSync());
   nonAsciiDir.createSync();
   Expect.isTrue(nonAsciiDir.existsSync());
-  var temp = new Directory("${tempDir.path}/æøå").createTempSync();
+  var temp = new Directory("${tempDir.path}/æøå").createTempSync('tempdir');
+  Expect.isTrue(temp.path.contains(precomposed) ||
+                temp.path.contains(decomposed));
+  temp.deleteSync();
+  temp = tempDir.createTempSync('æøå');
   Expect.isTrue(temp.path.contains(precomposed) ||
                 temp.path.contains(decomposed));
   temp.deleteSync();