Remove usage of dart:json.

samples/third_party/dromaeo/Dromaeo.dart

 library dromaeo_test;
 
 import 'dart:html';
 import 'dart:async';
-import 'dart:json' as json;
+import "dart:convert";
 import 'dart:math' as Math;
 import 'Suites.dart';
 
 main() {
   new Dromaeo().run();
 }
 
 class SuiteController {
   final SuiteDescription _suiteDescription;
   final IFrameElement _suiteIframe;
@@ skipping 75 matching lines @@
   final List<SuiteController> _suiteControllers;
   Function _handler;
 
   Dromaeo()
       : _suiteControllers = new List<SuiteController>()
   {
     _handler = _createHandler();
     window.onMessage.listen(
         (MessageEvent event) {
           try {
-            final response = json.parse(event.data);
+            final response = JSON.decode(event.data);
             _handler = _handler(response['command'], response['data']);
           } catch (e, stacktrace) {
             if (!(e is FormatException &&
                 (event.data.toString().startsWith('unittest') ||
                 event.data.toString().startsWith('dart')))) {
               // Hack because unittest also uses post messages to communicate.
               // So the fact that the event.data is not proper json is not
               // always an error.
               print('Exception: ${e}: ${stacktrace}');
               print(event.data);
@@ skipping 109 matching lines @@
   }
 
   Element _byId(String id) {
     return document.query('#$id');
   }
 
   int get _suitesTotal {
     return _suiteControllers.length;
   }
 }