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

examples/dart/hello_world/hello/main.dart

Index: examples/dart/hello_world/hello/main.dart
diff --git a/examples/dart/hello_world/hello/main.dart b/examples/dart/hello_world/hello/main.dart
index 4ff5e247f79848eee12ef636b5aeafbaa258570e..e3a73a848162e7728d5aa8e398fb8dbfd69d58d1 100644
--- a/examples/dart/hello_world/hello/main.dart
+++ b/examples/dart/hello_world/hello/main.dart
@@ -6,9 +6,10 @@
 // mojo_shell mojo:hello
 
 import 'dart:async';
-import 'dart:mojo.application';
-import 'dart:mojo.bindings';
-import 'dart:mojo.core';
+
+import 'package:mojo/public/dart/application.dart';
+import 'package:mojo/public/dart/bindings.dart';
+import 'package:mojo/public/dart/core.dart';
 
 class Hello extends Application {
   Hello.fromHandle(MojoHandle handle) : super.fromHandle(handle);