I've tried both Chrome and Safari and neither of them show this markup in the source. I tried to use Firefox, but it redirects to a search engine due to an issue with the character encoding of the page.
There's details of things to test in the pinned troubleshooting post. You should always check that the tags show up if the page is loaded via curl with the Twitterbot user-agent (e.g.
curl -A Twitterbot <your site>)