Remove usage of dart:json.

third_party/pkg/js/example/twitter/twitter.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.
 
 // A JS interop sample showing JSONP access to Twitter from Dart.
 
 import 'dart:html';
-import 'dart:json';
 import 'package:js/js.dart' as js;
 
 void main() {
   // Create a JavaScript function called display that forwards to the Dart
   // function.
   js.context.display = new js.Callback.once(display);
 
   // Inject a JSONP request to Twitter invoking the JavaScript display
   // function.
   document.body.nodes.add(new ScriptElement()..src =
@@ skipping 25 matching lines @@
   for (int i = 0; i < length; ++i) {
     var result = results[i];
     String user = result.from_user_name;
     String text = linkify(result.text);
 
     var div = new DivElement()
       ..innerHtml = '<div>From: $user</div><div>$text</div><p>';
     document.body.nodes.add(div);
   }
 }