The current major web rendering engines are EdgeHTML, Blink, WebKit, and Gecko. A web developer needs to test their site in all of them to make sure it works right.
However, there are two major implementations of Blink: Chrome and Opera. Is it necessary to test your site in both Chrome and Opera or can you safely assume that if it works in one it works in the other?
This is basically a current-day version of this question.
