I believe that the final bullet is the primary feature WebGL has been looking for: "a multi-application robustness extension that ensures that an application t

I believe that the final bullet is the primary feature WebGL has been looking for: "a multi-application robustness extension that ensures that an application that causes a GPU reset will not affect any other running applications." AFAIK the only remaining WebGL security concerns are DoS related, where misbehaving content can crash your drivers. There are no currently known leaks of data.