Small cleanup tasks. json and proto use the codec abstraction, but the binary serialization does not, other unrelated cleanup (#67)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index cf4b084..bd33166 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,7 +16,7 @@
 
 * Split the json codec from info.dart.
 
-* Introduced `lib/binary_codec.dart` a lighterweight
+* Introduced `lib/binary_serialization.dart` a lighterweight
   serialization/deserialization implementation. This will eventually be used by
   default by dart2js.
 
diff --git a/lib/binary_codec.dart b/lib/binary_serialization.dart
similarity index 100%
rename from lib/binary_codec.dart
rename to lib/binary_serialization.dart
diff --git a/lib/json_info_codec.dart b/lib/json_info_codec.dart
index 3a0f87f..92b7d63 100644
--- a/lib/json_info_codec.dart
+++ b/lib/json_info_codec.dart
@@ -49,12 +49,12 @@
         (elements['constant'] as Map).values.map((c) => parseConstant(c)));
 
     json['holding'].forEach((k, deps) {
-      var src = registry[k];
+      CodeInfo src = registry[k];
       assert(src != null);
       for (var dep in deps) {
         var target = registry[dep['id']];
         assert(target != null);
-        (src as CodeInfo).uses.add(new DependencyInfo(target, dep['mask']));
+        src.uses.add(new DependencyInfo(target, dep['mask']));
       }
     });
 
diff --git a/test/binary_codec_test.dart b/test/binary_serialization_test.dart
similarity index 95%
rename from test/binary_codec_test.dart
rename to test/binary_serialization_test.dart
index edbacb9..e38f3cb 100644
--- a/test/binary_codec_test.dart
+++ b/test/binary_serialization_test.dart
@@ -6,7 +6,7 @@
 import 'dart:io';
 
 import 'package:dart2js_info/json_info_codec.dart';
-import 'package:dart2js_info/binary_codec.dart' as binary;
+import 'package:dart2js_info/binary_serialization.dart' as binary;
 import 'package:test/test.dart';
 
 class ByteSink implements Sink<List<int>> {