anchor.diff:  import 'dart:async';
   import 'dart:html';
   import 'dart:json' as json;
  -import 'base.dart';
  +import 'streamy.dart';
   
   /// A [RequestHandler] that proxies through a frontend server.
   class ProxyClient extends RequestHandler {
  
positive.code:         if (resp.bodyType == 'application/json') {
            jsonError = json.parse(resp.body);
          }
          throw new ProxyException(resp.statusCode,
              'API call returned status: ${resp.statusText}', jsonError);
        }
        return req.responseDeserializer(resp.body);
      }).asStream();
    }
  }
  
  
negative.code:   ProxyClient(this.proxyUrl, {this.httpHandler: const DartHtmlHttpService()});
  
    Stream handle(Request req) {
      var c = new StreamController();
      var url = '$proxyUrl/${req.root.servicePath}${req.path}';
      var payload = req.hasPayload ? json.stringify(req.payload) : null;
      return httpHandler.request(url, req.httpMethod, payload: payload).then((resp) {
  