refactor: remove existsSync existsSync check.

Author: azu

lib/get-package-json.js

@@ -12,14 +12,16 @@ function findPackageDir(paths) {
     for (var i = 0; i < paths.length; ++i) {
         var dir = pather.dirname(paths[i]);
         var dirName = dir.split(pather.sep).pop();
-        if (dirName !== packageName && fs.existsSync(pather.join(dir, 'package.json'))) {
+        if (dirName !== packageName) {
             return dir;
         }
     }
 }
 /**
+ * find package.json directory and return package json.
+ * You should pass `module.paths` to `paths`.
  * @param {string[]} paths the paths for look-up
- * @returns {*}
+ * @returns {object}
  */
 function getPackageJSON(paths) {
     var dir = findPackageDir(paths);