Apparently this is for older versions of Opera as I had suspected. As of this year, versions of Opera are based on webkit, like chrome and safari.
This is quite an interesting development in web design. It may even signal the end of vendor prefixes altogether. Here are some interesting articles I found on the subject if you are interested:
https://gigaom.com/2013/02/13/why-is-opera-moving-to-webkit-because-it-has-to/
http://www.extremetech.com/computing/148312-opera-drops-presto-switch-to-google-and-apples-webkit-rendering-engine
http://www.webmonkey.com/2013/02/presto-is-dead-long-live-opera/
http://www.zdnet.com/time-to-move-on-final-patch-for-opera-12-due-by-mid-2014-7000023427/
http://www.sitepoint.com/opera-css3-webkit-prefix/
And last but not least:
http://www.nczonline.net/blog/2013/04/30/blink-and-the-end-of-vendor-prefixes/