module: simplify _resolveMain

remove check of execute bit for file-symlink as
it's always set. if file-symlink, just follow its target

Author: papercuptech

lib/module.js

@@ -255,14 +255,14 @@ if (process.platform === 'win32') {
       // path for dirver root like 'C:\node_modules' and don't need to
       // parse driver name.
       if (code === 92/*\*/ || code === 47/*/*/ || code === 58/*:*/ ||
-         (adjacentNodeModules && code === 46/*.*/)) {
+         (adjacentNodeModules && code === 43/*+*/)) {
         if (p !== nmLen) {
           var parent = from.slice(0, last);
           paths.push(parent + '\\node_modules');
 
           if (adjacentNodeModules) {
             paths.push(parent + '+node_modules');
-            if (code === 46/*.*/) {
+            if (code === 43/*+*/) {
               while (i > 1) {
                 const code = from.charCodeAt(--i);
                 if (code === 92/*\*/ || code === 47/*/*/ || code === 58/*:*/) {
@@ -306,14 +306,14 @@ if (process.platform === 'win32') {
     var last = from.length;
     for (var i = from.length - 1; i >= 0; --i) {
       const code = from.charCodeAt(i);
-      if (code === 47/*/*/ || (adjacentNodeModules && code === 46/*.*/)) {
+      if (code === 47/*/*/ || (adjacentNodeModules && code === 43/*+*/)) {
         if (p !== nmLen) {
           var parent = from.slice(0, last);
           paths.push(parent + '/node_modules');
 
           if (adjacentNodeModules) {
             paths.push(parent + '+node_modules');
-            if (code === 46/*.*/) {
+            if (code === 43/*+*/) {
               while (i > 1) {
                 if (from.charCodeAt(--i) === 47/*/*/) {
                   break;
@@ -434,8 +434,7 @@ Module._resolveLookupPaths = function(request, parent) {
   return [id, [path.dirname(parent.filename)]];
 };
 
-// when preserving symlinks, if the main file is both a file symlink AND
-// has execute permission (on windows, its extension is in PATHEXT), then
+// when preserving symlinks, if the main file is a file symlink then
 // its target is simply read and resolved, potentially relative to the
 // symlink's dirname. in all other cases the original path is preserved.
 Module._resolveMainRequest = function(request) {
@@ -448,23 +447,6 @@ Module._resolveMainRequest = function(request) {
     return request;
   }
 
-  let isExecutable = false;
-  if(process.platform === 'win32') {
-    const execExts = (process.env.PATHEXT || '').split(path.delimiter);
-    const requestExt = path.extname(request).toLowerCase();
-    isExecutable =
-      execExts.some((execExt) => requestExt === execExt.trim().toLowerCase());
-  } else {
-    try {
-      fs.accessSync(request, fs.constants.X_OK);
-      isExecutable = true;
-    } catch(e) {}
-  }
-
-  if(!isExecutable) {
-    return request;
-  }
-
   const targetPath = fs.readlinkSync(request);
   return path.isAbsolute(targetPath)
     ? targetPath