Remove unreachable code

Node.js < 4.5.0 is no longer supported as per
a2779222.

index.js

@@ -91,7 +91,6 @@ HttpsProxyAgent.prototype.callback = function connect(req, opts, fn) {
   }
 
   function cleanup() {
-    socket.removeListener('data', ondata);
     socket.removeListener('end', onend);
     socket.removeListener('error', onerror);
     socket.removeListener('close', onclose);
@@ -120,11 +119,7 @@ HttpsProxyAgent.prototype.callback = function connect(req, opts, fn) {
     if (!~str.indexOf('\r\n\r\n')) {
       // keep buffering
       debug('have not received end of HTTP headers yet...');
-      if (socket.read) {
-        read();
-      } else {
-        socket.once('data', ondata);
-      }
+      read();
       return;
     }
 
@@ -174,11 +169,7 @@ HttpsProxyAgent.prototype.callback = function connect(req, opts, fn) {
   function onsocket(socket) {
     // replay the "buffers" Buffer onto the `socket`, since at this point
     // the HTTP module machinery has been hooked up for the user
-    if ('function' == typeof socket.ondata) {
-      // node <= v0.11.3, the `ondata` function is set on the socket
-      socket.ondata(buffers, 0, buffers.length);
-    } else if (socket.listeners('data').length > 0) {
-      // node > v0.11.3, the "data" event is listened for directly
+    if (socket.listenerCount('data') > 0) {
       socket.emit('data', buffers);
     } else {
       // never?
@@ -193,11 +184,7 @@ HttpsProxyAgent.prototype.callback = function connect(req, opts, fn) {
   socket.on('close', onclose);
   socket.on('end', onend);
 
-  if (socket.read) {
-    read();
-  } else {
-    socket.once('data', ondata);
-  }
+  read();
 
   var hostname = opts.host + ':' + opts.port;
   var msg = 'CONNECT ' + hostname + ' HTTP/1.1\r\n';