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

mojo/dart/test/handle_finalizer_test.dart

Index: mojo/dart/test/handle_finalizer_test.dart
diff --git a/mojo/dart/test/handle_finalizer_test.dart b/mojo/dart/test/handle_finalizer_test.dart
index a3cd912f3d05522d7210c7c0d9389c1182dd261f..be4a7dc7c37c07492af779666f05e1cc2b802860 100644
--- a/mojo/dart/test/handle_finalizer_test.dart
+++ b/mojo/dart/test/handle_finalizer_test.dart
@@ -5,10 +5,9 @@
 import 'dart:async';
 import 'dart:isolate';
 import 'dart:typed_data';
-import 'dart:mojo.core';
-
 
 import 'package:mojo/dart/testing/expect.dart';
+import 'package:mojo/public/dart/core.dart';
 
 MojoHandle leakMojoHandle() {
   var pipe = new MojoMessagePipe();