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

tests/standalone/io/http_advanced_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.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
 
-#import("dart:isolate");
-#import("dart:io");
+import "dart:isolate";
+import "dart:io";
 
 class TestServerMain {
   TestServerMain()
       : _statusPort = new ReceivePort(),
         _serverPort = null {
     _serverPort = spawnFunction(startTestServer);
   }
 
   void setServerStartedHandler(void startedCallback(int port)) {
     _startedCallback = startedCallback;
@@ skipping 452 matching lines @@
         return testCookies().chain((_) {
           print('testFlush()');
           return testFlush();
         });
       });
     });
   }).then((_) {
     print('done');
   });
 }