Get rid of all the library tags.

lib/src/io.dart

 // Copyright (c) 2014, 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.
 
-library http.io;
-
 @MirrorsUsed(targets: const ['dart.io.HttpClient', 'dart.io.HttpException',
   'dart.io.File'])
 import 'dart:mirrors';
 
 /// Whether `dart:io` is supported on this platform.
 bool get supported => _library != null;
 
 /// The `dart:io` library mirror, or `null` if it couldn't be loaded.
 final _library = _getLibrary();
 
@@ skipping 31 matching lines @@
 
 /// Tries to load `dart:io` and returns `null` if it fails.
 LibraryMirror _getLibrary() {
   try {
     return currentMirrorSystem().findLibrary(const Symbol('dart.io'));
   } catch (_) {
     // TODO(nweiz): narrow the catch clause when issue 18532 is fixed.
     return null;
   }
 }