[v0.6] Don't use `agent.appendMessage()`

Instead, just perform a request.

lib/node-http-proxy/http-proxy.js

@@ -599,11 +599,12 @@ HttpProxy.prototype.proxyWebSocketRequest = function (req, socket, head, buffer)
   //
   outgoing.host    = this.target.host;
   outgoing.port    = this.target.port;
+  outgoing.agent   = agent;
   outgoing.method  = 'GET';
   outgoing.path    = req.url;
   outgoing.headers = req.headers;
   
-  var reverseProxy = agent.appendMessage(outgoing);
+  var reverseProxy = this.target.protocol.request(outgoing);
 
   //
   // On any errors from the `reverseProxy` emit the