fs: fix permanent deoptimizations

PR-URL: #12456 Reviewed-By: Benjamin Gruenbaum <[email protected]> Reviewed-By: James M Snell <[email protected]>

Author: mscdex

lib/fs.js

@@ -60,8 +60,8 @@ function getOptions(options, defaultOptions){
 }
 
 functioncopyObject(source){
-consttarget={};
-for(constkeyinsource)
+vartarget={};
+for(varkeyinsource)
 target[key]=source[key];
 returntarget;
 }
@@ -273,7 +273,7 @@ fs.existsSync = function(path){
 };
 
 fs.readFile=function(path,options,callback){
-callback=maybeCallback(arguments[arguments.length-1]);
+callback=maybeCallback(callback||options);
 options=getOptions(options,{flag: 'r'});
 
 if(handleError((path=getPathFromURL(path)),callback))
@@ -1249,9 +1249,7 @@ fs.futimesSync = function(fd, atime, mtime){
 binding.futimes(fd,atime,mtime);
 };
 
-functionwriteAll(fd,isUserFd,buffer,offset,length,position,callback_){
-varcallback=maybeCallback(arguments[arguments.length-1]);
-
+functionwriteAll(fd,isUserFd,buffer,offset,length,position,callback){
 // write(fd, buffer, offset, length, position, callback)
 fs.write(fd,buffer,offset,length,position,function(writeErr,written){
 if(writeErr){
@@ -1282,7 +1280,7 @@ function writeAll(fd, isUserFd, buffer, offset, length, position, callback_){
 }
 
 fs.writeFile=function(path,data,options,callback){
-callback=maybeCallback(arguments[arguments.length-1]);
+callback=maybeCallback(callback||options);
 options=getOptions(options,{encoding: 'utf8',mode: 0o666,flag: 'w'});
 constflag=options.flag||'w';