Fix shadowing in tests. Constructor and method are not allowed to have

tests/standalone/io/testing_server.dart

Index: tests/standalone/io/testing_server.dart
diff --git a/tests/standalone/io/testing_server.dart b/tests/standalone/io/testing_server.dart
index 6ff5fc38ccdf54d7b518b955f04e6109d57cabc4..22356df153ad5aa5ed0195f0732a05ded1082db1 100644
--- a/tests/standalone/io/testing_server.dart
+++ b/tests/standalone/io/testing_server.dart
@@ -35,12 +35,12 @@ class TestingServerTest {
   TestingServerTest.start(SendPort port)
       : _receivePort = new ReceivePort(),
         _sendPort = port {
-    start();
+    initialize();
   }
 
   abstract void run();
 
-  void start() {
+  void initialize() {
     _receivePort.receive((var message, SendPort replyTo) {
       _port = message;
       run();