Update pkg/http to use the new async APIs.

pkg/http/test/mock_client_test.dart

Index: pkg/http/test/mock_client_test.dart
diff --git a/pkg/http/test/mock_client_test.dart b/pkg/http/test/mock_client_test.dart
index 01581a8197cea2381ec4ad0f6272f72098c7b0a2..02e713b00b6bb1d2abd1c59394609ac79e6b1932 100644
--- a/pkg/http/test/mock_client_test.dart
+++ b/pkg/http/test/mock_client_test.dart
@@ -34,12 +34,11 @@ void main() {
 
   test('handles a streamed request', () {
     var client = new MockClient.streaming((request, bodyStream) {
-      return consumeInputStream(bodyStream).then((body) {
-        var stream = new ListInputStream();
+      return bodyStream.bytesToString().then((bodyString) {
+        var stream = new StreamController<List<int>>.singleSubscription();
         async.then((_) {
-          var bodyString = new String.fromCharCodes(body);
-          stream.write('Request body was "$bodyString"'.charCodes);
-          stream.markEndOfStream();
+          stream.add('Request body was "$bodyString"'.charCodes);
+          stream.close();
         });
 
         return new http.StreamedResponse(stream, 200, -1);