Dart: Removes all but native calls and the handle watcher from the snapshot.

mojo/dart/test/codec_test.dart

Index: mojo/dart/test/codec_test.dart
diff --git a/mojo/dart/test/codec_test.dart b/mojo/dart/test/codec_test.dart
index 676054a22bf236bc6198709af0f8dc60e71435f0..a1a71cc34f61eb7bd0efb667bfaf9246afeb3914 100644
--- a/mojo/dart/test/codec_test.dart
+++ b/mojo/dart/test/codec_test.dart
@@ -3,8 +3,9 @@
 // found in the LICENSE file.
 
 import 'dart:typed_data';
-import 'dart:mojo.bindings' as bindings;
-import 'dart:mojo.core' as core;
+
+import 'package:mojo/public/dart/bindings.dart' as bindings;
+import 'package:mojo/public/dart/core.dart' as core;
 
 import 'package:mojo/dart/testing/expect.dart';