Add generic argument to Codec.fuse.

sdk/lib/convert/codec.dart

Index: sdk/lib/convert/codec.dart
diff --git a/sdk/lib/convert/codec.dart b/sdk/lib/convert/codec.dart
index 3fc2d31256c8d5afc075377814125cdb070a1557..7f42c862357dad7d62df3e21a19d5f05e19518e1 100644
--- a/sdk/lib/convert/codec.dart
+++ b/sdk/lib/convert/codec.dart
@@ -62,8 +62,8 @@ abstract class Codec<S, T> {
    */
   // TODO(floitsch): use better example with line-splitter once that one is
   // in this library.
-  Codec<S, dynamic> fuse(Codec<T, dynamic> other) {
-    return new _FusedCodec<S, T, dynamic>(this, other);
+  Codec<S, dynamic/*=R*/> fuse/*<R>*/(Codec<T, dynamic/*=R*/> other) {
+    return new _FusedCodec<S, T, dynamic/*=R*/>(this, other);
   }
 
   /**