Don't append newlines inside a span

I'm working on an atom to jekyll converter, and found a bug where this construction (which is popular in Blogger):

<a href='http://example.com'><div style='bar'>Text</div></a>

would cause output like this:

[Text

](http://example.com)

Which jekyll barfs on because it doesn't like newlines inside a link span. This fixes that problem.