module: avoid hasOwnProperty()

hasOwnProperty() is known to be slow, do a direct lookup on a "clean"
object instead.

PR-URL: https://github.com/nodejs/node/pull/10789
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

lib/module.js

@@ -33,14 +33,6 @@ const internalModuleReadFile = process.binding('fs').internalModuleReadFile;
 const internalModuleStat = process.binding('fs').internalModuleStat;
 const preserveSymlinks = !!process.binding('config').preserveSymlinks;
 
-// If obj.hasOwnProperty has been overridden, then calling
-// obj.hasOwnProperty(prop) will break.
-// See: https://github.com/joyent/node/issues/1707
-function hasOwnProperty(obj, prop) {
-  return Object.prototype.hasOwnProperty.call(obj, prop);
-}
-
-
 function stat(filename) {
   filename = path._makeLong(filename);
   const cache = stat.cache;
@@ -95,12 +87,12 @@ const debug = Module._debug;
 //   -> a/index.<ext>
 
 // check if the directory is a package.json dir
-const packageMainCache = {};
+const packageMainCache = Object.create(null);
 
 function readPackage(requestPath) {
-  if (hasOwnProperty(packageMainCache, requestPath)) {
-    return packageMainCache[requestPath];
-  }
+  const entry = packageMainCache[requestPath];
+  if (entry)
+    return entry;
 
   const jsonPath = path.resolve(requestPath, 'package.json');
   const json = internalModuleReadFile(path._makeLong(jsonPath));