Broken HTML code when using special Unicode characters in title

When using a special Unicode character in the title (like 🎄 – 🎄) the twitter button which is generated below a post is creating broken HTML:

<!-- Twitter Button --><div class="twitter-button" id="twitter-content-buttons-post-302"><a href="http://twitter.com/share" class="twitter-share-button" data-lang="en" data-url="http://packagedrone.org/2015/12/23/merry-christmas-2015/" data-counturl="http://packagedrone.org/2015/12/23/merry-christmas-2015/" data-text=" </div>

See the “data-text” attribute which suddenly ends.

https://ww.wp.xz.cn/plugins/nextgen-facebook/