Remove DirectoryException and LinkException from dart:io and use FileException instaed.

tests/standalone/io/file_read_encoded_test.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.
 
 import "package:expect/expect.dart";
 import "package:async_helper/async_helper.dart";
 import 'dart:io';
 
 void testReadAsString() {
   var tmp = Directory.systemTemp.createTempSync('dart_file_read_encoded');
 
   var file = new File('${tmp.path}/file');
   file.createSync();
 
   file.writeAsBytesSync([0xb0]);
 
-  Expect.throws(file.readAsStringSync, (e) => e is FileException);
+  Expect.throws(file.readAsStringSync, (e) => e is FileSystemException);
 
   asyncStart();
   file.readAsString().then((_) {
     Expect.fail("expected exception");
   }).catchError((e) {
     tmp.deleteSync(recursive: true);
     asyncEnd();
-  }, test: (e) => e is FileException);
+  }, test: (e) => e is FileSystemException);
 }
 
 void testReadAsLines() {
   var tmp = Directory.systemTemp.createTempSync('dart_file_read_encoded');
 
   var file = new File('${tmp.path}/file');
   file.createSync();
 
   file.writeAsBytesSync([0xb0]);
 
-  Expect.throws(file.readAsLinesSync, (e) => e is FileException);
+  Expect.throws(file.readAsLinesSync, (e) => e is FileSystemException);
 
   asyncStart();
   file.readAsLines().then((_) {
     Expect.fail("expected exception");
   }).catchError((e) {
     tmp.deleteSync(recursive: true);
     asyncEnd();
-  }, test: (e) => e is FileException);
+  }, test: (e) => e is FileSystemException);
 }
 
 void main() {
   testReadAsString();
   testReadAsLines();
 }