Typing animation don't respect mask

[jcubic]

Issue summary

If you use typing animation on input that is masked the text is visible.

Expected behavior

I should see typing animation with mask

Actual behavior

I can see the text on the terminal

Steps to reproduce

1. Create terminal with login
2. Call term.exec(['guest', 'guest'], { typing: true });

Browser and OS

NA

Additional notes

$('body').terminal({}, {
    login(username, password) {
        if (username === 'guest' && password === 'guest') {
            return '<TOKEN>';
        }
    }
});
term.exec(['guest', 'guest'], { typing: true });

Note: that in master the not async login function doesn't work (it was already fixed).