Fix listing of '' and '/'.

runtime/bin/directory_macos.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_MACOS)
 
 #include "bin/directory.h"
 
 #include <dirent.h>  // NOLINT
@@ skipping 61 matching lines @@
   LinkList* next;
 };
 
 
 ListType DirectoryListingEntry::Next(DirectoryListing* listing) {
   if (done_) {
     return kListDone;
   }
 
   if (lister_ == 0) {
-    if (!listing->path_buffer().Add(File::PathSeparator())) {
-      done_ = true;
-      return kListError;
-    }
-    path_length_ = listing->path_buffer().length();
     do {
       lister_ = reinterpret_cast<intptr_t>(
           opendir(listing->path_buffer().AsString()));
     } while (lister_ == 0 && errno == EINTR);
 
     if (lister_ == 0) {
       done_ = true;
       return kListError;
     }
+    if (parent_ != NULL) {
+      if (!listing->path_buffer().Add(File::PathSeparator())) {
+        return kListError;
+      }
+    }
+    path_length_ = listing->path_buffer().length();
   }
   // Reset.
   listing->path_buffer().Reset(path_length_);
   ResetLink();
 
   // Iterate the directory and post the directories and files to the
   // ports.
   int status = 0;
   dirent entry;
   dirent* result;
@@ skipping 319 matching lines @@
 bool Directory::Rename(const char* path, const char* new_path) {
   ExistsResult exists = Exists(path);
   if (exists != EXISTS) return false;
   return (TEMP_FAILURE_RETRY(rename(path, new_path)) == 0);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)