Fix fs.realpathSync on windows

lib/fs.js

@@ -512,7 +512,7 @@ if (isWindows) {
   // the same as path.resolve that fails if the path doesn't exists.
 
   // windows version
-  fs.realpathSync = function realpathSync(p) {
+  fs.realpathSync = function realpathSync(p, cache) {
     var p = path.resolve(p);
     if (cache && Object.prototype.hasOwnProperty.call(cache, p)) {
       return cache[p];