Make pub strong-mode clean.

lib/src/asset/dart/serialize.dart

Index: lib/src/asset/dart/serialize.dart
diff --git a/lib/src/asset/dart/serialize.dart b/lib/src/asset/dart/serialize.dart
index f95022d65f38c28e3e380621eb297bfa88721fe7..7af294171080c45bf04820e8a4dd77d20e0e3000 100644
--- a/lib/src/asset/dart/serialize.dart
+++ b/lib/src/asset/dart/serialize.dart
@@ -5,6 +5,7 @@
 import 'dart:async';
 import 'dart:isolate';
 
+import 'package:async/async.dart';
 import 'package:barback/barback.dart';
 
 //# if source_span
@@ -12,7 +13,6 @@ import 'package:source_span/source_span.dart';
 //# end
 
 import 'serialize/exception.dart';
-import 'utils.dart';
 
 export 'serialize/aggregate_transform.dart';
 export 'serialize/exception.dart';
@@ -77,7 +77,7 @@ SourceLocation deserializeLocation(Map location) {
 /// Converts [stream] into a serializable map.
 ///
 /// [serializeEvent] is used to serialize each event from the stream.
-Map serializeStream(Stream stream, serializeEvent(event)) {
+Map serializeStream/*<T>*/(Stream/*<T>*/ stream, serializeEvent(/*=T*/ event)) {
   var receivePort = new ReceivePort();
   var map = {'replyTo': receivePort.sendPort};
 
@@ -102,8 +102,9 @@ Map serializeStream(Stream stream, serializeEvent(event)) {
 /// Converts a serializable map into a [Stream].
 ///
 /// [deserializeEvent] is used to deserialize each event from the stream.
-Stream deserializeStream(Map stream, deserializeEvent(event)) {
-  return callbackStream(() {
+Stream/*<T>*/ deserializeStream/*<T>*/(Map stream,
+    /*=T*/ deserializeEvent(event)) {
+  return new LazyStream(() {
     var receivePort = new ReceivePort();
     stream['replyTo'].send({'replyTo': receivePort.sendPort});
 
@@ -133,15 +134,18 @@ Stream deserializeStream(Map stream, deserializeEvent(event)) {
 ///
 /// The returned Future will complete to the value or error returned by
 /// [respond].
-Future call(SendPort port, message) {
+Future/*<T>*/ call/*<T>*/(SendPort port, message) {
   var receivePort = new ReceivePort();
   port.send({
     'message': message,
     'replyTo': receivePort.sendPort
   });
 
-  return receivePort.first.then((response) {
-    if (response['type'] == 'success') return response['value'];
+  return new Future.sync(() async {
+    var response = await receivePort.first;
+    if (response['type'] == 'success') {
+      return response['value'] as dynamic/*=T*/;
+    }
     assert(response['type'] == 'error');
     var exception = deserializeException(response['error']);
     return new Future.error(exception, exception.stackTrace);