http: fix legacy http.Client instanceof

lib/http.js

@@ -95,5 +95,8 @@ Client.prototype.request = function(method, path, headers) {
 exports.Client = internalUtil.deprecate(Client, 'http.Client is deprecated.');
 
 exports.createClient = internalUtil.deprecate(function(port, host) {
-  return new Client(port, host);
+  const client = new Client(port, host);
+  // Need to set the prototype of the deprecated class to fix `instanceof`.
+  Object.setPrototypeOf(client, exports.Client.prototype);
+  return client;
 }, 'http.createClient is deprecated. Use http.request instead.');

test/parallel/test-http-legacy.js

@@ -38,6 +38,7 @@ var server = http.createServer(function(req, res) {
 
 server.listen(0, common.mustCall(function() {
   var client = http.createClient(this.address().port);
+  assert(client instanceof http.Client);
   var req = client.request('/hello', {'Accept': '*/*', 'Foo': 'bar'});
   setTimeout(function() {
     req.end();