Comment 2 for bug 23632

While it is very annoying, I personally think it is something that should be
dealt with the site owners, not with at the browser level since this "feature"
is intentionally done by the web site authors, using standard features of the
Javascript language.

But if you really need to access right-click options for a site, simply disable
javascript, or go into Edit --> Preference --> Web Features --> Javascript
Advanced and unselect "Disable or replace content". If you do the later, you
still get the warning the site authors wanted you to see, but it is immediatelly
followed by the right-click menu. At least that's the behaviour at
http://www.formula1.com/