Implement fullPath method on File objects.

runtime/bin/file.dart

 // Copyright (c) 2011, 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.
 
 interface File factory _File {
   /**
    * Create a File object.
    */
   File(String name);
 
@@ skipping 142 matching lines @@
    * called when the flush operation completes.
    */
    void flush();
 
   /**
    * Synchronously flush the contents of the file to disk.
    */
   void flushSync();
 
   /**
+   * Get the canonical full path corresponding to the file name. The
+   * [fullPathHandler] is called when the fullPath operation
+   * completes.
+   */
+  String fullPath();
+
+  /**
+   * Synchronously get the canonical full path corresponding to the file name.
+   */
+  String fullPathSync();
+
+  /**
    * Create a new independent input stream for the file. The file
    * input stream must be closed when no longer used.
    */
   FileInputStream openInputStream();
 
   /**
    * Creates a new independent output stream for the file. The file
    * output stream must be closed when no longer used.
    */
   FileOutputStream openOutputStream();
 
   /**
    * Get the name of the file.
    */
   String get name();
 
   // Event handlers.
   void set existsHandler(void handler(bool exists));
   void set createHandler(void handler());
   void set openHandler(void handler());
   void set closeHandler(void handler());
   void set readByteHandler(void handler(int byte));
   void set readListHandler(void handler(int read));
   void set noPendingWriteHandler(void handler());
   void set positionHandler(void handler(int position));
   void set lengthHandler(void handler(int length));
   void set flushHandler(void handler());
+  void set fullPathHandler(void handler(String path));
   void set errorHandler(void handler(String error));
 }
 
 
 interface FileInputStream extends InputStream {
   void close();
 }
 
 
 interface FileOutputStream extends OutputStream {
 }
 
 
 class FileIOException implements Exception {
   const FileIOException([String this.message = ""]);
   String toString() => "FileIOException: $message";
   final String message;
 }