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

tests/standalone/io/http_headers_state.dart

Index: tests/standalone/io/http_headers_state.dart
diff --git a/tests/standalone/io/http_headers_state.dart b/tests/standalone/io/http_headers_state.dart
index c84c7fabdaaaee1adb4768a3c4b4b8f0110aaa4e..d5a3f01f2d4daeedcb5cc83e9c432ff2b4b51a5f 100644
--- a/tests/standalone/io/http_headers_state.dart
+++ b/tests/standalone/io/http_headers_state.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 test(int totalConnections, [String body]) {
   HttpServer server = new HttpServer();