add comments for dart:io and dart:intl library

pkg/intl/intl.dart

Index: pkg/intl/intl.dart
diff --git a/pkg/intl/intl.dart b/pkg/intl/intl.dart
index feb8580ce6ba98de64fa36eae2df0c220f09810d..521e1c2f8733164ba7debcf49acda11de8a29bdc 100644
--- a/pkg/intl/intl.dart
+++ b/pkg/intl/intl.dart
@@ -2,6 +2,10 @@
 // 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.
 
+/**
+ * Internationalization object providing access to message formatting objects,
+ * date formatting, parsing, bidirectional text relative to a specific locale.
+ */
 #library('intl');
 
 #import('dart:web');
@@ -11,11 +15,6 @@
 #source('bidi_formatter.dart');
 #source('bidi_utils.dart');
 
-/**
- * Internationalization object providing access to message formatting objects,
- * date formatting, parsing, bidirectional text relative to a specific locale.
- */
-
 class Intl {
   /**
    * String indicating the locale code with which the message is to be