Fix directory-listing to return a future on cancel.

runtime/bin/directory_win.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_WINDOWS)
 
 #include "bin/directory.h"
 #include "bin/file.h"
 #include "bin/utils.h"
@@ skipping 188 matching lines @@
   if (FindNextFileW(reinterpret_cast<HANDLE>(lister_), &find_file_data) != 0) {
     return HandleFindFile(listing, this, find_file_data);
   }
 
   done_ = true;
 
   if (GetLastError() != ERROR_NO_MORE_FILES) {
     return kListError;
   }
 
-  if (FindClose(reinterpret_cast<HANDLE>(lister_)) == 0) {
-    return kListError;
-  }
-
   return kListDone;
 }
 
 
+DirectoryListingEntry::~DirectoryListingEntry() {
+  ResetLink();
+  if (lister_ != 0) {
+    FindClose(reinterpret_cast<HANDLE>(lister_));
+  }
+}
+
+
 void DirectoryListingEntry::ResetLink() {
   if (link_ != NULL && (parent_ == NULL || parent_->link_ != link_)) {
     delete link_;
     link_ = NULL;
   }
   if (parent_ != NULL) {
     link_ = parent_->link_;
   }
 }
 
@@ skipping 239 matching lines @@
       MoveFileExW(system_path, system_new_path, flags);
   free(const_cast<wchar_t*>(system_path));
   free(const_cast<wchar_t*>(system_new_path));
   return (move_status != 0);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)