Remove old #import, #source, and #library syntax from tests/standalone.

tests/standalone/io/directory_error_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.
 //
 // Dart test program for testing error handling in directory I/O.
 
-#import("dart:io");
-#import("dart:isolate");
+import "dart:io";
+import "dart:isolate";
 
 Directory tempDir() {
   return new Directory('').createTempSync();
 }
 
 
 bool checkCreateInNonExistentFileException(e) {
   Expect.isTrue(e is DirectoryIOException);
   Expect.isTrue(e.osError != null);
   Expect.isTrue(e.toString().indexOf("Creation failed") != -1);
@@ skipping 197 matching lines @@
 main() {
   runTest(testCreateInNonExistent);
   runTest(testCreateTempInNonExistent);
   runTest(testDeleteNonExistent);
   runTest(testDeleteRecursivelyNonExistent);
   runTest(testListNonExistent);
   runTest(testRenameNonExistent);
   runTest(testRenameFileAsDirectory);
   runTest(testRenameOverwriteFile);
 }