Twitter card meta data non-valid syntax according to the W3C

While checking my document i noticed the Twitter card meta data syntax isn’t HTML5 valid according to the W3C recommendation.

To get your HTML5 document validated you can change the syntax within file class-twitter.php :
<meta name=”twitter should become <meta property=”twitter (use the property attribute).

After updating the syntax i did a test via Twitter preview tool. All worked fine.

Site i am referring to : http://advertbanner.com

http://wordpress.org/extend/plugins/wordpress-seo/