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

tests/standalone/io/echo_server_test.dart

Index: tests/standalone/io/echo_server_test.dart
diff --git a/tests/standalone/io/echo_server_test.dart b/tests/standalone/io/echo_server_test.dart
index 23e95ffa55753f6dc81e43e26fe2e8c42e3abd43..9850225f6fd796ccb919a23c68b36f2705b4a766 100644
--- a/tests/standalone/io/echo_server_test.dart
+++ b/tests/standalone/io/echo_server_test.dart
@@ -36,7 +36,7 @@ class EchoServerGame {
       _buffer[i] = FIRSTCHAR + i;
     }
     _sendPort = spawnFunction(startEchoServer);
-    start();
+    initialize();
   }
 
   void sendData() {
@@ -107,7 +107,7 @@ class EchoServerGame {
     }
   }
 
-  void start() {
+  void initialize() {
     _receivePort.receive((var message, SendPort replyTo) {
       _port = message;
       sendData();