Use sky_shell instead of mojo_shell for testing.

sky/tests/services/resources/iframe-vmc.js

-#!mojo mojo:js_content_handler
-
-define("main", [
-  "console",
-  "mojo/public/js/bindings",
-  "mojo/services/public/js/application",
-  "mojo/services/view_manager/public/interfaces/view_manager.mojom",
-  "services/js/test/echo_service.mojom",
-], function(console, bindings, application, viewManagerMojom, echoServiceMojom) {
-
-  const Application = application.Application;
-  const ViewManagerClient = viewManagerMojom.ViewManagerClient;
-  const EchoService = echoServiceMojom.EchoService;
-
-  var serviceImpl;
-  var success = new Promise(function(resolve) {
-    serviceImpl = {
-      onEmbed: function() {
-        resolve({value: "success"});
-      },
-      echoString: function(s) {
-        return success;
-      },
-    }
-  });
-
-  class IFrameVMCApp extends Application {
-    acceptConnection(initiatorURL, initiatorServiceExchange) {
-      var factory = function() { return serviceImpl; }
-      initiatorServiceExchange.provideService(ViewManagerClient, factory);
-      initiatorServiceExchange.provideService(EchoService, factory);
-    }
-  }
-
-  return IFrameVMCApp;
-});