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

tests/standalone/io/test_extension_fail_tester.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.
 
-#library("test_extension_test");
+library test_extension_test;
 
-#import("dart:isolate");
-#import('test_extension.dart');
+import "dart:isolate";
+import "test_extension.dart";
 
 main() {
   try {
     Cat.throwMeTheBall("ball");
   } on String catch (e) {
     Expect.equals("ball", e);
   }
   // Make sure the exception is thrown out to the event handler from C++ code.
   // The harness expects the string "ball" to be thrown and the process to
   // end with an unhandled exception.
   new Timer(0, (_) => Cat.throwMeTheBall("ball"));
 }