Update to latest dependencies, require dart 2.1, fix lints

lib/src/dart.dart

@@ -109,7 +109,7 @@ class AnalysisContextManager {
   ///
   /// Throws [AnalyzerErrorGroup] is the file has parsing errors.
   CompilationUnit parse(String path) {
-    var parseResult = _getExistingSession(path).getParsedAstSync(path);
+    var parseResult = _getExistingSession(path).getParsedUnit(path);
     if (parseResult.errors.isNotEmpty) {
       throw AnalyzerErrorGroup(parseResult.errors);
     }

pubspec.yaml

@@ -2,18 +2,18 @@ name: pub
 publish_to: none
 
 environment:
-  sdk: ">=2.0.0 <3.0.0"
+  sdk: ">=2.1.0 <3.0.0"
 
 dependencies:
   # Note: Pub's test infrastructure assumes that any dependencies used in tests
   # will be hosted dependencies.
-  analyzer: ^0.33.0
+  analyzer: ^0.35.0
   args: ^1.4.1
   async: ^2.0.0
   collection: ^1.8.0
-  crypto: ">=1.0.0 <3.0.0"
+  crypto: ^2.0.0
   http: ^0.12.0
-  http_multi_server: ">=1.0.0 <3.0.0"
+  http_multi_server: ^2.0.0
   http_retry: ^0.1.1
   http_throttle: ^1.0.0
   meta: ^1.1.0

test/oauth2/with_a_server_rejected_refresh_token_authenticates_again_test.dart

@@ -2,8 +2,8 @@
 // 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 'dart:convert';
 import 'dart:async';
+import 'dart:convert';
 
 import 'package:shelf/shelf.dart' as shelf;
 import 'package:shelf_test_handler/shelf_test_handler.dart';