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

tests/standalone/io/http_server_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.
 
-#import("dart:io");
-#import("dart:isolate");
+import "dart:io";
+import "dart:isolate";
 
 void testListenOn() {
   ServerSocket socket = new ServerSocket("127.0.0.1", 0, 5);
 
   socket.onError = (Exception e) {
     Expect.fail("ServerSocket closed unexpected");
   };
 
   void test(void onDone()) {
     HttpServer server = new HttpServer();
@@ skipping 39 matching lines @@
   test(() {
     test(() {
       socket.close();
     });
   });
 }
 
 void main() {
   testListenOn();
 }