http: misc cleanup and minor optimizations

PR-URL: https://github.com/nodejs/node/pull/6533
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

lib/_http_server.js

@@ -88,6 +88,8 @@ function ServerResponse(req) {
   if (req.method === 'HEAD') this._hasBody = false;
 
   this.sendDate = true;
+  this._sent100 = false;
+  this._expect_continue = false;
 
   if (req.httpVersionMajor < 1 || req.httpVersionMinor < 1) {
     this.useChunkedEncodingByDefault = chunkExpression.test(req.headers.te);
@@ -195,8 +197,7 @@ function writeHead(statusCode, reason, obj) {
   if (common._checkInvalidHeaderChar(this.statusMessage))
     throw new Error('Invalid character in statusMessage.');
 
-  var statusLine = 'HTTP/1.1 ' + statusCode.toString() + ' ' +
-                   this.statusMessage + CRLF;
+  var statusLine = 'HTTP/1.1 ' + statusCode + ' ' + this.statusMessage + CRLF;
 
   if (statusCode === 204 || statusCode === 304 ||
       (100 <= statusCode && statusCode <= 199)) {
@@ -232,7 +233,7 @@ function Server(requestListener) {
   net.Server.call(this, { allowHalfOpen: true });
 
   if (requestListener) {
-    this.addListener('request', requestListener);
+    this.on('request', requestListener);
   }
 
   /* eslint-disable max-len */
@@ -242,7 +243,7 @@ function Server(requestListener) {
   /* eslint-enable max-len */
   this.httpAllowHalfOpen = false;
 
-  this.addListener('connection', connectionListener);
+  this.on('connection', connectionListener);
 
   this.timeout = 2 * 60 * 1000;