Replicating CL https://chromiumcodereview.appspot.com/11553012/

pkg/serialization/lib/src/serialization_helpers.dart

Index: pkg/serialization/lib/src/serialization_helpers.dart
diff --git a/pkg/serialization/lib/src/serialization_helpers.dart b/pkg/serialization/lib/src/serialization_helpers.dart
index df4b2cf285d0c38e28de414868e61c494b9f21f8..a9980b8d812712d7c2cbd48ea8ec5587b2299a7f 100644
--- a/pkg/serialization/lib/src/serialization_helpers.dart
+++ b/pkg/serialization/lib/src/serialization_helpers.dart
@@ -200,6 +200,4 @@ class IdentityMapPlus<K, V> extends IdentityMap {
    * Note that keys is a very inefficient operation for this type. Don't do it.
    */
   get keys => super.keys.map((x) => unwrap(x));
-}
-
-
+}