Add prefix.

utils/pub/hosted_source.dart

 // 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.
 
 library hosted_source;
 
 import 'dart:io' as io;
 import 'dart:json';
 import 'dart:uri';
 
@@ skipping 73 matching lines @@
     }).chain((_) {
       // Now that the install has succeeded, move it to the real location in
       // the cache. This ensures that we don't leave half-busted ghost
       // directories in the user's pub cache if an install fails.
       var rename = renameDir(tempDir, destPath);
 
       // TODO(rnystrom): Awful hack. On Windows, we see cases where the extract
       // has not finished by the time we get here, so the rename fails with a
       // "directory in use" error. So, we will just wait a couple of seconds
       // before we start.
-      if (Platform.operatingSystem == "windows") {
+      if (io.Platform.operatingSystem == "windows") {
         rename = sleep(2000).chain((_) => rename);
       }
 
       return rename;
     }).transform((_) => true);
   }
 
   /**
    * The system cache directory for the hosted source contains subdirectories
    * for each separate repository URL that's used on the system. Each of these
@@ skipping 48 matching lines @@
 
     var name = description["name"];
     if (name is! String) {
       throw new FormatException("The 'name' key must have a string value.");
     }
 
     var url = description.containsKey("url") ? description["url"] : defaultUrl;
     return new Pair<String, String>(name, url);
   }
 }