http: define all used properties in constructors

Adding all used properties in the constructor makes the hidden class
stable and heap snapshots more verbose.

Refs: https://github.com/nodejs/node/issues/8912
PR-URL: https://github.com/nodejs/node/pull/9116
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>

lib/_http_client.js

@@ -135,6 +135,14 @@ function ClientRequest(options, cb) {
                       self._renderHeaders());
   }
 
+  this._ended = false;
+  this.res = null;
+  this.aborted = undefined;
+  this.timeoutCb = null;
+  this.upgradeOrConnect = false;
+  this.parser = null;
+  this.maxHeadersCount = null;
+
   var called = false;
   if (self.socketPath) {
     self._last = true;
@@ -202,16 +210,12 @@ function ClientRequest(options, cb) {
     self._flush();
     self = null;
   });
-
-  this._ended = false;
 }
 
 util.inherits(ClientRequest, OutgoingMessage);
 
 exports.ClientRequest = ClientRequest;
 
-ClientRequest.prototype.aborted = undefined;
-
 ClientRequest.prototype._finish = function _finish() {
   DTRACE_HTTP_CLIENT_REQUEST(this, this.connection);
   LTTNG_HTTP_CLIENT_REQUEST(this, this.connection);
@@ -225,7 +229,7 @@ ClientRequest.prototype._implicitHeader = function _implicitHeader() {
 };
 
 ClientRequest.prototype.abort = function abort() {
-  if (this.aborted === undefined) {
+  if (!this.aborted) {
     process.nextTick(emitAbortNT, this);
   }
   // Mark as aborting so we can avoid sending queued request data
@@ -454,7 +458,7 @@ function parserOnIncomingClient(res, shouldKeepAlive) {
 
   if (res.statusCode === 100) {
     // restart the parser, as this is a continue message.
-    delete req.res; // Clear res so that we don't hit double-responses.
+    req.res = null; // Clear res so that we don't hit double-responses.
     req.emit('continue');
     return true;
   }

lib/_http_server.js

@@ -248,6 +248,7 @@ function Server(requestListener) {
   this.timeout = 2 * 60 * 1000;
 
   this._pendingResponseData = 0;
+  this.maxHeadersCount = null;
 }
 util.inherits(Server, net.Server);