http: revert deprecation of client property

The improper deprecation of the property broke a feature in the
request module used by the bundled npm. This reverts the deprecation
part of this change.

PR-URL: https://github.com/nodejs/io.js/pull/1852
Fixes: https://github.com/nodejs/io.js/issues/1850
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Roman Reiss <me@silverwind.io>

lib/_http_incoming.js

@@ -47,7 +47,7 @@ function IncomingMessage(socket) {
   // response (client) only
   this.statusCode = null;
   this.statusMessage = null;
-  this._client = socket; // deprecated
+  this.client = socket;
 
   // flag for backwards compatibility grossness.
   this._consuming = false;
@@ -61,16 +61,6 @@ util.inherits(IncomingMessage, Stream.Readable);
 
 exports.IncomingMessage = IncomingMessage;
 
-Object.defineProperty(IncomingMessage.prototype, 'client', {
-  configurable: true,
-  enumerable: true,
-  get: util.deprecate(function() {
-    return this._client;
-  }, 'client is deprecated, use socket or connection instead'),
-  set: util.deprecate(function(val) {
-    this._client = val;
-  }, 'client is deprecated, use socket or connection instead')
-});
 
 IncomingMessage.prototype.setTimeout = function(msecs, callback) {
   if (callback)