Add FileException.path and clean up file exceptions.

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;
 
 /**
  * FileMode describes the modes in which a file can be opened.
  */
 class FileMode {
@@ skipping 507 matching lines @@
   String toString();
 
   /**
    * Gets the path of the file underlying this RandomAccessFile.
    */
   String get path;
 }
 
 
 class FileException implements IOException {
+  final String message;
+  final String path;
+  final OSError osError;
   const FileException([String this.message = "",
-                         OSError this.osError = null]);
+                       String this.path = "",
+                       OSError this.osError]);
+
   String toString() {
     StringBuffer sb = new StringBuffer();
     sb.write("FileException");
     if (!message.isEmpty) {
       sb.write(": $message");
+      if (path != null) {
+        sb.write(", path = $path");
+      }
       if (osError != null) {
         sb.write(" ($osError)");
       }
     } else if (osError != null) {
       sb.write(": osError");
+      if (path != null) {
+        sb.write(", path = $path");
+      }
     }
     return sb.toString();
   }
-  final String message;
-  final OSError osError;
 }