Remove library dart:crypto

tests/standalone/io/http_proxy_test.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.
 
+import "package:crypto/crypto.dart";
 import "package:expect/expect.dart";
 import "dart:async";
-import 'dart:crypto';
 import "dart:io";
 import 'dart:utf';
 
 class Server {
   HttpServer server;
   bool secure;
   int proxyHops;
   List<String> directRequestPaths;
   int requestCount = 0;
 
@@ skipping 742 matching lines @@
   testProxyFromEnviroment();
   // The two invocations of uses the same global variable for state -
   // run one after the other.
   testProxyAuthenticate(false)
       .then((_) => testProxyAuthenticate(true));
   // This test is not normally run. It can be used for locally testing
   // with a real proxy server (e.g. Apache).
   //testRealProxy();
   //testRealProxyAuth();
 }