fs: un-deprecate existsSync(), throw error on EPERM

doc/api/fs.markdown

@@ -367,11 +367,14 @@ non-existent.
 
 ## fs.existsSync(path)
 
-    Stability: 0 - Deprecated: Use [fs.statSync][] or [fs.accessSync][] instead.
-
 Synchronous version of [`fs.exists`][].
 Returns `true` if the file exists, `false` otherwise.
 
+Note: this function will throw on Windows if an EPERM error is returned by the
+underlying `fs.statSync()` call. However, it is not suggested to attempt to
+catch this error. Instead, the end user probably needs to fix the file's
+permissions by hand.
+
 ## fs.fchmod(fd, mode, callback)
 
 Asynchronous fchmod(2). No arguments other than a possible exception

lib/fs.js

@@ -223,6 +223,9 @@ fs.existsSync = function(path) {
     binding.stat(pathModule._makeLong(path));
     return true;
   } catch (e) {
+    if (e.code === 'EPERM')
+      throw e; // EPERM means we no longer knows if it exists or not.
+
     return false;
   }
 };