Add FileSystemEntity.absolutePath and .isAbsolute properties.

sdk/lib/io/directory.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.
 
 part of dart.io;
 
 /**
  * [Directory] objects are used for working with directories.
  */
 abstract class Directory implements FileSystemEntity {
@@ skipping 91 matching lines @@
    * Synchronously renames this directory. Returns a [Directory]
    * instance for the renamed directory.
    *
    * If newPath identifies an existing directory, that directory is
    * replaced. If newPath identifies an existing file the operation
    * fails and an exception is thrown.
    */
   Directory renameSync(String newPath);
 
   /**
+   * Returns a [Directory] instance whose path is the absolute path to [this].
+   *
+   * The absolute path is computed by prefixing
+   * a relative path with the current working directory, and returning
+   * an absolute path unchanged.
+   */
+  Directory get absolute;
+
+  /**
    * Lists the sub-directories and files of this [Directory].
    * Optionally recurses into sub-directories.
    *
    * If [followLinks] is false, then any symbolic links found
    * are reported as [Link] objects, rather than as directories or files,
    * and are not recursed into.
    *
    * If [followLinks] is true, then working links are reported as
    * directories or files, depending on
    * their type, and links to directories are recursed into.
@@ skipping 64 matching lines @@
       if (path != null) {
         sb.write(", path = $path");
       }
     }
     return sb.toString();
   }
   final String message;
   final String path;
   final OSError osError;
 }