Stop supporting map literals with 1 type argument

utils/pub/curl_client.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 curl_client;
 
 import 'dart:async';
 import 'dart:io';
 
 import '../../pkg/http/lib/http.dart' as http;
@@ skipping 143 matching lines @@
     // line. We just care about the last block. There is one trailing empty
     // line, though, which we don't want to consider a separator.
     var lastBlank = lines.lastIndexOf("", lines.length - 2);
     if (lastBlank != -1) lines.removeRange(0, lastBlank + 1);
 
     var statusParts = lines.removeAt(0).split(" ");
     var status = int.parse(statusParts[1]);
     var isRedirect = status >= 300 && status < 400;
     var reasonPhrase =
         Strings.join(statusParts.getRange(2, statusParts.length - 2), " ");
-    var headers = <String>{};
+    var headers = <String, String>{};
     for (var line in lines) {
       if (line.isEmpty) continue;
       var split = split1(line, ":");
       headers[split[0].toLowerCase()] = split[1].trim();
     }
     var responseStream = process.stdout;
     if (responseStream.closed) {
       responseStream = new ListInputStream();
       responseStream.markEndOfStream();
     }
@@ skipping 14 matching lines @@
   /// path to the bundled `curl.exe`; elsewhere, this is just "curl", and we
   /// assume it to be installed and on the user's PATH.
   static String get _defaultExecutable {
     if (Platform.operatingSystem != 'windows') return 'curl';
     // Note: This line of code gets munged by create_sdk.py to be the correct
     // relative path to curl in the SDK.
     var pathToCurl = "../../third_party/curl/curl.exe";
     return relativeToPub(pathToCurl);
   }
 }