Typo fix in Dom plugin, Dynamic popup with iframe fix

This particular dynamic popup issue might be a corner case scenario, however here is the scenario which is causing the problem for us.

We dynamically create an activity stream which contains photos and videos mixed within the days activities, the goal is to have those photos and videos open in a dynamic popup, however the standard pure html popup code does not properly place the overlay at the end of the document causing it to instead just dim the screen, to remedy this we added the following event
```
$$(document).on('click', '.create-popup', function () {
    var $target = $$(this), html = $$($target.data('popup')).html();
    f7.popup(html);
});
```

which grabs the popup div and feeds it into the dynamic popup method;  Below is an example of the html it is grabbing.

```
<a href="#activity-videos-popup-{{id}}" data-popup=".activity-videos-popup-{{id}}" class="create-popup ui-link">
    <img src="{{content_data.thumb}}" class="alignleft" alt="{{content_data.caption}}" />
</a>
<div class="activity-videos-popup-{{id}}">
    <div id="activity-videos-popup-{{id}}" class="popup popup-video">
        <div class="content-block">
            <a href="#" class="close-popup">Close</a>
            <div class="select-items">
                <div class="select-items-head">
                    <h3>{{content_data.caption}}</h3>
                </div>
                {{getVideoHtml content_data.url}}
            </div>
        </div>
    </div>
</div>
```

we were getting the following error
"Uncaught TypeError: Cannot read property 'add' of undefined       framework7.js:1811" after debugging I determined the problem was the hard coded location in the childNodes on line 1810 by looping through the childNodes and looking for the actual div, it fixed this particular problem for us.