Remove usage of dart:json.

pkg/http/test/utils.dart

 // Copyright (c) 2013, 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 test_utils;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
-import 'dart:json' as json;
 
 import 'package:http/src/byte_stream.dart';
 import 'package:http/src/utils.dart';
 import 'package:unittest/unittest.dart';
 
 import 'safe_http_server.dart';
 
 /// The current server instance.
 HttpServer _server;
 
@@ skipping 68 matching lines @@
         };
         if (requestBody != null) content['body'] = requestBody;
         request.headers.forEach((name, values) {
           // These headers are automatically generated by dart:io, so we don't
           // want to test them here.
           if (name == 'cookie' || name == 'host') return;
 
           content['headers'][name] = values;
         });
 
-        var body = json.stringify(content);
+        var body = JSON.encode(content);
         response.contentLength = body.length;
         response.write(body);
         response.close();
       });
     });
   });
 }
 
 /// Stops the current HTTP server.
 void stopServer() {
@@ skipping 37 matching lines @@
 class _Parse extends Matcher {
   final Matcher _matcher;
 
   _Parse(this._matcher);
 
   bool matches(item, Map matchState) {
     if (item is! String) return false;
 
     var parsed;
     try {
-      parsed = json.parse(item);
+      parsed = JSON.decode(item);
     } catch (e) {
       return false;
     }
 
     return _matcher.matches(parsed, matchState);
   }
 
   Description describe(Description description) {
     return description.add('parses to a value that ')
       .addDescriptionOf(_matcher);
@@ skipping 32 matching lines @@
 const isSocketException = const _SocketException();
 
 /// A matcher for functions that throw SocketException.
 const Matcher throwsSocketException =
     const Throws(isSocketException);
 
 class _SocketException extends TypeMatcher {
   const _SocketException() : super("SocketException");
   bool matches(item, Map matchState) => item is SocketException;
 }