ShellApp+ShellGlobal: unify app launch context code

Extend shell_global_create_app_launch_context() with the required
parameters and use that for shell_app_launch() too.

https://bugzilla.gnome.org/show_bug.cgi?id=669603

js/misc/util.js

@@ -89,7 +89,7 @@ function spawnApp(argv) {
         let app = Gio.AppInfo.create_from_commandline(argv.join(' '), null,
                                                       Gio.AppInfoCreateFlags.SUPPORTS_STARTUP_NOTIFICATION);
 
-        let context = global.create_app_launch_context();
+        let context = global.create_app_launch_context(0, -1);
         app.launch([], context);
     } catch(err) {
         _handleSpawnError(argv[0], err);