pub site: update dependencies and fix analyzer

app/lib/upload_signer_service.dart

 // Copyright (c) 2015, 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 pub_dartlang_org.upload_signer_service;
 
 import 'dart:async';
 import 'dart:convert';
 
-import 'package:crypto/crypto.dart';
 import 'package:googleapis_auth/src/crypto/rsa_sign.dart';
 import 'package:googleapis_auth/src/crypto/pem.dart' as pem;
 import 'package:googleapis_auth/src/crypto/rsa.dart' as rsa;
 
 import 'package:gcloud/service_scope.dart' as ss;
 import 'package:pub_server/repository.dart';
 
 import 'keys.dart';
 
 /// The registered [UploadSignerService] object.
@@ skipping 45 matching lines @@
         {'expires' : expirationString},
         {'success_action_redirect' : successRedirectUrl},
         ['content-length-range', 0, maxUploadSize],
     ];
 
     var policyMap = {
         'expiration' : expirationString,
         'conditions' : conditions,
     };
 
-    var policyString =
-        CryptoUtils.bytesToBase64(UTF8.encode(JSON.encode(policyMap)));
-    var signatureString =
-        CryptoUtils.bytesToBase64(_signer.sign(ASCII.encode(policyString)));
+    var policyString = BASE64.encode(UTF8.encode(JSON.encode(policyMap)));
+    var signatureString = BASE64.encode(_signer.sign(ASCII.encode(policyString)));
 
     var fields = {
         'key' : object,
         'acl' : predefinedAcl,
         'Expires' : expirationString,
         'GoogleAccessId' : serviceAccountEmail,
         'policy' : policyString,
         'signature' : signatureString,
         'success_action_redirect' : successRedirectUrl,
     };
 
     return new AsyncUploadInfo(UploadUrl, fields);
   }
 }