Fix Directory, File and Link constructor text.

sdk/lib/io/file.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;
 
 /**
  * The modes in which a File can be opened.
  */
 class FileMode {
@@ skipping 157 matching lines @@
  * a section from _A Tour of the Dart Libraries_
  * covers files and directories.
  *
  * * [Write Command-Line Apps](https://www.dartlang.org/docs/tutorials/cmdline/),
  * a tutorial about writing command-line apps, includes information
  * about files and directories.
 
  */
 abstract class File extends FileSystemEntity {
   /**
-   * Create a File object.
+   * Creates a [File] object.
+   *
+   * The path is either an absolute path,
+   * or it is a relative path which is interpreted relative to the current
+   * working directory (see [Directory.current]).
    */
   factory File(String path) => new _File(path);
 
   /**
    * Create a File object from a URI.
    *
    * If [uri] cannot reference a file this throws [UnsupportedError].
    */
   factory File.fromUri(Uri uri) => new File(uri.toFilePath());
 
@@ skipping 545 matching lines @@
       sb.write(": $osError");
       if (path != null) {
         sb.write(", path = '$path'");
       }
     } else if (path != null) {
       sb.write(": $path");
     }
     return sb.toString();
   }
 }