Don't use "=>" for void methods in delegates.

lib/src/delegate/stream_sink.dart

Index: lib/src/delegate/stream_sink.dart
diff --git a/lib/src/delegate/stream_sink.dart b/lib/src/delegate/stream_sink.dart
index 9742b4ce066a115b12badf2f873fc5bae9693884..b6ace650cb14c3d70a7ce711d8f1d890312c4d30 100644
--- a/lib/src/delegate/stream_sink.dart
+++ b/lib/src/delegate/stream_sink.dart
@@ -19,10 +19,13 @@ class DelegatingStreamSink<T> implements StreamSink<T> {
   DelegatingStreamSink(StreamSink sink)
       : _sink = sink;
 
-  void add(T data) => _sink.add(data);
+  void add(T data) {
+    _sink.add(data);
+  }
 
-  void addError(error, [StackTrace stackTrace]) =>
-      _sink.addError(error, stackTrace);
+  void addError(error, [StackTrace stackTrace]) {
+    _sink.addError(error, stackTrace);
+  }
 
   Future addStream(Stream<T> stream) => _sink.addStream(stream);