var timeout = 500;
var w = window.open('http://moikrug.ru/threads/junk/', '_blank');

function waitFor(f) {
  setTimeout(function() {
    try {
      f();
    } catch (e) { 
      console.log('waitFor(): ' + e);
      waitFor(f);
    }
  }, timeout);
}

function waitClass(w) {
  waitFor(function() {
    var elem = w.document.getElementsByClassName('b-mk-actions__link')[0];
    var href = elem.getAttribute('href');
    var ww = window.open(href, '_blank');
    waitFor(function() {
      ww.document.getElementById('not_junk_form').submit();
      waitClass(ww);
      w.close();
    })
  })
}

waitClass(w);