Empty inline elements are removed from the embedded content

[Szymon Cofalik]

When autoembeding content, sometimes we end up with empty inline elements, which are then removed from the embedded content.

Steps to reproduce:

1. In empty editor, paste http://tellto.tumblr.com/post/112160646328.
2. Wait until the link converts.
3. Look at source.

Expected result: There should be inline elements in <div data-oembed-url="http://tellto.tumblr.com/post/112160646328"> or the link should be correctly converted.
Result:

<div data-oembed-url="http://tellto.tumblr.com/post/112160646328">
<script async="" charset="utf-8" src="//cdn.iframe.ly/embed.js"></script>
</div>

Which has no graphical representation in WYSIWYG mode.