javafx2 application (browser or webstart) running in sandbox missing exitVM/stopThread permission

this is because in AppPolicy.addSandboxPermissionsObject, currently we have code:

  if (JNLPClassLoaderUtil.getInstance() instanceof JNLPClassLoader) {
            perms.add(new RuntimePermission("exitVM"));
            perms.add(new RuntimePermission("stopThread"));
        }

When running with FX2 application - this check might fail. If it's the JavaFX application thread, the thread's context class loader will either be the bootclassloader, or just a vanila URLClassLoader. It won't be instanceof JNLPClassLoaderIf. And it will not be instanceof JNLPClassLoader either - because FX2 applications will always be loaded by JNLP2ClassLoader now.

I believe it's okay to grant these 2 permissions for FX2 sandbox application always - because FX2 applications will always run in it's own JVM, no matter it's browser based or webstart. (similar to awt webstart application) There is no sharing of JVM between FX2 applications for now.