Remove deprecated parts of dart:async.

tests/standalone/io/http_server_test.dart

Index: tests/standalone/io/http_server_test.dart
diff --git a/tests/standalone/io/http_server_test.dart b/tests/standalone/io/http_server_test.dart
index f5018b492b7dbead6da7951364623353ebdb5e65..00dc5cd9f068032eba98947b69fc8f29e34c1552 100644
--- a/tests/standalone/io/http_server_test.dart
+++ b/tests/standalone/io/http_server_test.dart
@@ -28,9 +28,8 @@ void testListenOn() {
             onDone();
           });
       })
-      .catchError((e) {
+      .catchError((e, trace) {
         String msg = "Unexpected error in Http Client: $e";
-        var trace = getAttachedStackTrace(e);
         if (trace != null) msg += "\nStackTrace: $trace";
         Expect.fail(msg);
       });