dart:io | Add asynchronous versions of the methods of FileSystemEntity and Link.

sdk/lib/io/link.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.
 
 part of dart.io;
 
 /**
  * [Link] objects are references to filesystem links.
  *
  */
@@ skipping 186 matching lines @@
       return this;
     });
   }
 
   void deleteSync() {
     var result = _File._deleteLink(path);
     throwIfError(result, "Cannot delete link '$path'");
   }
 
   Future<String> target() {
-    // TODO(whesse): Replace with asynchronous version.
-    return new Future.sync(targetSync);
+    _ensureFileService();
+    List request = new List(2);
+    request[0] = _LINK_TARGET_REQUEST;
+    request[1] = path;
+    return _fileService.call(request).then((response) {
+      if (_isErrorResponse(response)) {
+        throw _exceptionFromResponse(response,
+            "Cannot get target of link '$path'");
+      }
+      return response;
+    });
   }
 
   String targetSync() {
     var result = _File._linkTarget(path);
     throwIfError(result, "Cannot read link '$path'");
     return result;
   }
 
   static throwIfError(Object result, String msg) {
     if (result is OSError) {
@@ skipping 47 matching lines @@
       if (path != null) {
         sb.write(", path = $path");
       }
     }
     return sb.toString();
   }
   final String message;
   final String path;
   final OSError osError;
 }