Enable dartanalyze warnings.

services/dart/test/pingpong/main.dart

Index: services/dart/test/pingpong/main.dart
diff --git a/services/dart/test/pingpong/main.dart b/services/dart/test/pingpong/main.dart
index 5c10d354e18ee8c50b0931dc549a9a6d7c1341ab..5b4b4e1af6cfdce2cd5214ff211292f9a633f3c9 100644
--- a/services/dart/test/pingpong/main.dart
+++ b/services/dart/test/pingpong/main.dart
@@ -51,7 +51,8 @@ class PingPongServiceImpl implements PingPongService {
     }
   }
 
-  Future pingTargetUrl(String url, int count, Function responseFactory) async {
+  Future pingTargetUrl(String url, int count,
+      [Function responseFactory = null]) async {

[zra, 2015/03/11 18:38:06]

default is already null when not specified.

[Elliot Glaysher, 2015/03/11 19:19:18]

I am unsure what resolution you're asking for here. I've speculatively removed '
= null' from every case that you mentioned. If that's not the correct resolution
here, please be specific in you're followup comments.

[zra, 2015/03/11 19:32:57]

Ah, yes. Sorry for not being more explicit.

     if (_application == null) {
       return responseFactory(false);
     }
@@ -72,8 +73,8 @@ class PingPongServiceImpl implements PingPongService {
     return responseFactory(true);
   }
 
-  Future pingTargetService(
-      ProxyBase proxyBase, int count, Function responseFactory) async {
+  Future pingTargetService(ProxyBase proxyBase, int count,
+      [Function responseFactory = null]) async {

[zra, 2015/03/11 18:38:06]

ditto

     var pingPongService = proxyBase;
     var completer = new Completer();
     var client = new PingPongClientImpl.unbound(count, completer);