Begin migrating the vm service from a rest-style interface to a json-rpc style interface.

runtime/bin/vmservice/vmservice_dartium.dart

Index: runtime/bin/vmservice/vmservice_dartium.dart
diff --git a/runtime/bin/vmservice/vmservice_dartium.dart b/runtime/bin/vmservice/vmservice_dartium.dart
index 99f04fa8dbcf686e90d013159f8e8b7a9f481caf..6a1b7b79782688fa72d47b4ccec057d8720269c0 100644
--- a/runtime/bin/vmservice/vmservice_dartium.dart
+++ b/runtime/bin/vmservice/vmservice_dartium.dart
@@ -38,8 +38,8 @@ class DartiumClient extends Client {
     });
   }
 
-  void post(var seq, String response) {
-    postResponse(response, seq);
+  void post(var serial, String response) {
+    postResponse(response, serial);
   }
 
   dynamic toJson() {