Make pub strong-mode clean.

lib/src/asset/dart/serialize/transform.dart

 // Copyright (c) 2014, 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 'dart:async';
 import 'dart:isolate';
 
 import 'package:barback/barback.dart';
 // TODO(nweiz): don't import from "src" once issue 14966 is fixed.
 import 'package:barback/src/internal_asset.dart';
 
 import '../serialize.dart';
 import 'get_input_transform.dart';
 
 /// Serialize the methods shared between [Transform] and [DeclaringTransform].
 ///
 /// [additionalFields] contains additional serialized fields to add to the
 /// serialized transform. [methodHandlers] is a set of additional methods. Each
 /// value should take a JSON message and return the response (which may be a
 /// Future).
-Map _serializeBaseTransform(transform, Map additionalFields,
+Map _serializeBaseTransform(transform, Map<String, dynamic> additionalFields,
     Map<String, Function> methodHandlers) {
   var receivePort = new ReceivePort();
   receivePort.listen((wrappedMessage) {
     respond(wrappedMessage, (message) {
       var handler = methodHandlers[message['type']];
       if (handler != null) return handler(message);
 
       if (message['type'] == 'consumePrimary') {
         transform.consumePrimary();
         return null;
       }
 
       assert(message['type'] == 'log');
       var method = {
         'Info': transform.logger.info,
         'Fine': transform.logger.fine,
         'Warning': transform.logger.warning,
         'Error': transform.logger.error
       }[message['level']];
       assert(method != null);
 
       var assetId = message['assetId'] == null ? null :
         deserializeId(message['assetId']);
       var span = message['span'] == null ? null :
         deserializeSpan(message['span']);
       method(message['message'], asset: assetId, span: span);
     });
   });
 
-  return {'port': receivePort.sendPort}..addAll(additionalFields);
+  return <String, dynamic>{'port': receivePort.sendPort}
+      ..addAll(additionalFields);
 }
 
 /// Converts [transform] into a serializable map.
 Map serializeTransform(Transform transform) {
   return _serializeBaseTransform(transform, {
     'primaryInput': serializeAsset(transform.primaryInput)
   }, {
     'getInput': (message) => transform.getInput(deserializeId(message['id']))
         .then((asset) => serializeAsset(asset)),
     'addOutput': (message) =>
@@ skipping 76 matching lines @@
       : primaryId = deserializeId(transform['primaryId']),
         super(transform);
 
   void declareOutput(AssetId id) {
     call(_port, {
       'type': 'declareOutput',
       'output': serializeId(id)
     });
   }
 }