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

tests/standalone/io/string_stream_test.dart

Index: tests/standalone/io/string_stream_test.dart
diff --git a/tests/standalone/io/string_stream_test.dart b/tests/standalone/io/string_stream_test.dart
index d1369dcceec3637a1a9d5f4f97c271332aea1488..4ef05349556e01b77c90265a3da162765c6429bb 100644
--- a/tests/standalone/io/string_stream_test.dart
+++ b/tests/standalone/io/string_stream_test.dart
@@ -2,8 +2,8 @@
 // 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 testUtf8() {
   List<int> data = [0x01,