process: fix permanent deoptimizations

PR-URL: https://github.com/nodejs/node/pull/12456
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/internal/process/stdio.js

@@ -51,7 +51,7 @@ function setupStdio() {
 
     switch (tty_wrap.guessHandleType(fd)) {
       case 'TTY':
-        const tty = require('tty');
+        var tty = require('tty');
         stdin = new tty.ReadStream(fd, {
           highWaterMark: 0,
           readable: true,
@@ -60,13 +60,13 @@ function setupStdio() {
         break;
 
       case 'FILE':
-        const fs = require('fs');
+        var fs = require('fs');
         stdin = new fs.ReadStream(null, { fd: fd, autoClose: false });
         break;
 
       case 'PIPE':
       case 'TCP':
-        const net = require('net');
+        var net = require('net');
 
         // It could be that process has been started with an IPC channel
         // sitting on fd=0, in such case the pipe for this fd is already
@@ -152,20 +152,20 @@ function createWritableStdioStream(fd) {
 
   switch (tty_wrap.guessHandleType(fd)) {
     case 'TTY':
-      const tty = require('tty');
+      var tty = require('tty');
       stream = new tty.WriteStream(fd);
       stream._type = 'tty';
       break;
 
     case 'FILE':
-      const fs = require('internal/fs');
+      var fs = require('internal/fs');
       stream = new fs.SyncWriteStream(fd, { autoClose: false });
       stream._type = 'fs';
       break;
 
     case 'PIPE':
     case 'TCP':
-      const net = require('net');
+      var net = require('net');
       stream = new net.Socket({
         fd: fd,
         readable: false,