Add more test cases

[orthecreedence]

<div class="button-row">
    <!--
    <div class="button huge firefox">
        <a href="/download/firefox-latest.xpi">
            <h2>Turtl <em>v0.1.0</em></h2>
            <small>(Firefox >= 21)</small>
        </a>
    </div>
    -->
    <div class="button huge chrome">
        <a href="/download/chrome-latest.crx">
            <h2>Turtl <em>v0.1.9</em></h2>
            <small>(Chrome >= 28)</small>
        </a>
    </div>
</div>

<img src="my-image.jpg">

<div class=\"twitter\">
<a class=\"twitter-timeline\" data-dnt=\"true\" href=\"https://twitter.com/turtlapp\"  data-widget-id=\"382037759679934465\">Tweets by @turtlapp</a>
<script>!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0],p=/^http:/.test(d.location)?'http':'https';if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src=p+\"://platform.twitter.com/widgets.js\";fjs.parentNode.insertBefore(js,fjs);}}(document,\"script\",\"twitter-wjs\");</script>
</div>

Note that XMLS tends to mangle <a> tags with no body:

<a id="asdf"></a>

...think of more (things that have been issues in the past)