Sky should expose services provided to/by embedder

sky/examples/dart-mojo.sky

Index: sky/examples/dart-mojo.sky
diff --git a/sky/examples/dart-mojo.sky b/sky/examples/dart-mojo.sky
index c540292739a9acc26d064fe72707c1fd0b9cc7e8..cee9de92d13e0db47fc7f89523478e7bd5d80058 100644
--- a/sky/examples/dart-mojo.sky
+++ b/sky/examples/dart-mojo.sky
@@ -74,7 +74,7 @@ main() {
   var messagePipe = new MojoMessagePipe();
   var wget = new WGet(messagePipe.endpoints[1]);
   wget.listen();
-  var shellProxy = new shell_mojom.ShellProxy.fromHandle(new MojoHandle(internals.passShellProxyHandle()));
+  var shellProxy = new shell_mojom.ShellProxy.fromHandle(new MojoHandle(internals.takeShellProxyHandle()));
   wget.initializeFromShellProxy(shellProxy, ["mojo:wget", "http://www.google.com"], "mojo:wget");
 }