Inserting into body after assigning event handlers

Otherwise, e.g. when the script is already cached, IE may sometimes not fire the `load` event (`readyState` instantly becomes `"complete"`) - it's funny, because IE should not do anything (incl. checks for event handlers!) before the current tick of event loop ends... similar case: http://stackoverflow.com/questions/18414964/load-event-for-iframe-does-not-fire-in-ie