Stop supporting map literals with 1 type argument

pkg/oauth2/lib/src/utils.dart

 // Copyright (c) 2012, 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 utils;
 
 import 'dart:async';
 import 'dart:uri';
 import 'dart:isolate';
 import 'dart:crypto';
 
 /// Adds additional query parameters to [url], overwriting the original
 /// parameters if a name conflict occurs.
 Uri addQueryParameters(Uri url, Map<String, String> parameters) {
   var queryMap = queryToMap(url.query);
   mapAddAll(queryMap, parameters);
   return url.resolve("?${mapToQuery(queryMap)}");
 }
 
 /// Convert a URL query string (or `application/x-www-form-urlencoded` body)
 /// into a [Map] from parameter names to values.
 Map<String, String> queryToMap(String queryList) {
-  var map = <String>{};
+  var map = <String, String>{};
   for (var pair in queryList.split("&")) {
     var split = split1(pair, "=");
     if (split.isEmpty) continue;
     var key = urlDecode(split[0]);
     var value = split.length > 1 ? urlDecode(split[1]) : "";
     map[key] = value;
   }
   return map;
 }
 
@@ skipping 73 matching lines @@
     if (!paramString.trim().isEmpty) {
       throw new FormatException('Invalid WWW-Authenticate header: "$header"');
     }
 
     return new AuthenticateHeader(scheme, parameters);
   }
 }
 
 /// Returns a [Future] that asynchronously completes to `null`.
 Future get async => new Future.delayed(0, () => null);