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

tests/standalone/io/http_shutdown_test.dart

Index: tests/standalone/io/http_shutdown_test.dart
diff --git a/tests/standalone/io/http_shutdown_test.dart b/tests/standalone/io/http_shutdown_test.dart
index 1d19e962a2db86ff100dacbad3b38fd5ae3b2dcc..c7e3bbef5ec972b6e4aaa8fb6b7bb66e4792d1cb 100644
--- a/tests/standalone/io/http_shutdown_test.dart
+++ b/tests/standalone/io/http_shutdown_test.dart
@@ -3,8 +3,8 @@
 // BSD-style license that can be found in the LICENSE file.
 //
 
-#import("dart:isolate");
-#import("dart:io");
+import "dart:isolate";
+import "dart:io";
 
 void test1(int totalConnections) {
   // Server which just closes immediately.