Error stack strawman

[Steve Fink]

On 02/24/2016 01:30 PM, Mark S. Miller wrote:
> [2] This solves only one of the cross-realm issue with stacks. It does 
> nothing to address worries about cross-realm stacks.
>

We do have code in FF that handles cross-realm stacks, or at least a 
close moral equivalent to them. The stacks are stored internally as 
objects, and each frame records where it comes from, so a user will only 
see frames that it has privileges for. Obviously, once you convert to a 
string, you're past the point of control.

(Or at least, that's my understanding of what is going on. I'm not sure 
if that stuff is used for Error.stack yet.)