Whonix uses two virtual machines, one to run tor and the other only connects to the first, so you could (in theory) literally run anything as root on the Workstation one and it couldn't get your IP address. Even Adobe Flash, or javascript, or a browser with zero days. The only thing that could get you is a zero day in virtualbox itself, and even that would still need a privilege escalation first. For more details see https://www.whonix.org/wiki/Comparison_with_Others#Attacks
(I may be slightly overselling it, but it is definitely more secure than tails. Only very advanced extremists use it.)