Fix most strong mode warnings.

lib/src/stream_sink_completer.dart

 // Copyright (c) 2016, 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 'null_stream_sink.dart';
 
 /// A [sink] where the destination is provided later.
 ///
@@ skipping 18 matching lines @@
   /// Returns [sink] typed as a [_CompleterSink].
   _CompleterSink<T> get _sink => sink;
 
   /// Convert a `Future<StreamSink>` to a `StreamSink`.
   ///
   /// This creates a sink using a sink completer, and sets the destination sink
   /// to the result of the future when the future completes.
   ///
   /// If the future completes with an error, the returned sink will instead
   /// be closed. Its [Sink.done] future will contain the error.
-  static StreamSink fromFuture(Future<StreamSink> sinkFuture) {
-    var completer = new StreamSinkCompleter();
+  static StreamSink/*<T>*/ fromFuture/*<T>*/(
+      Future<StreamSink/*<T>*/> sinkFuture) {
+    var completer = new StreamSinkCompleter/*<T>*/();
     sinkFuture.then(completer.setDestinationSink,
         onError: completer.setError);
     return completer.sink;
   }
 
   /// Sets a sink as the destination for events from the [StreamSinkCompleter]'s
   /// [sink].
   ///
   /// The completer's [sink] will act exactly as [destinationSink].
   ///
@@ skipping 118 matching lines @@
           .catchError((_) {});
     }
 
     // If the user has already asked when the sink is done, connect the sink's
     // done callback to that completer.
     if (_doneCompleter != null) {
       _doneCompleter.complete(sink.done);
     }
   }
 }