net: Initialize _connection, _handle in Socket ctor

The better to reduce the hidden classes

lib/net.js

@@ -127,6 +127,9 @@ function initSocketHandle(self) {
 function Socket(options) {
   if (!(this instanceof Socket)) return new Socket(options);
 
+  this._connecting = false;
+  this._handle = null;
+
   switch (typeof options) {
     case 'number':
       options = { fd: options }; // Legacy interface.