module: use "clean" objects

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

@@ -69,9 +69,9 @@ function Module(id, parent) {
 }
 module.exports = Module;
 
-Module._cache = {};
-Module._pathCache = {};
-Module._extensions = {};
+Module._cache = Object.create(null);
+Module._pathCache = Object.create(null);
+Module._extensions = Object.create(null);
 var modulePaths = [];
 Module.globalPaths = [];