Work around issue 9278.

utils/pub/io.dart

 // Copyright (c) 2013, 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.
 
 /// Helper functionality to make working with IO easier.
 library io;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:isolate';
@@ skipping 183 matching lines @@
 
 /// Returns whether [dir] exists on the file system. This will return `true` for
 /// a symlink only if that symlink is unbroken and points to a directory.
 bool dirExists(String dir) => new Directory(dir).existsSync();
 
 /// Deletes whatever's at [path], whether it's a file, directory, or symlink. If
 /// it's a directory, it will be deleted recursively.
 void deleteEntry(String path) {
   if (linkExists(path)) {
     log.io("Deleting link $path.");
-    new Link(path).deleteSync();
+    if (Platform.operatingSystem == 'windows') {
+      // TODO(nweiz): remove this when issue 9278 is fixed.
+      new Directory(path).deleteSync();
+    } else {
+      new Link(path).deleteSync();
+    }
   } else if (dirExists(path)) {
     log.io("Deleting directory $path.");
     new Directory(path).deleteSync(recursive: true);
   } else {
     log.io("Deleting file $path.");
     new File(path).deleteSync();
   }
 }
 
 /// "Cleans" [dir]. If that directory already exists, it will be deleted. Then a
@@ skipping 551 matching lines @@
   const PubProcessResult(this.stdout, this.stderr, this.exitCode);
 
   bool get success => exitCode == 0;
 }
 
 /// Gets a [Uri] for [uri], which can either already be one, or be a [String].
 Uri _getUri(uri) {
   if (uri is Uri) return uri;
   return Uri.parse(uri);
 }