Error stack

[Brendan Eich]

I have a sinking feeling it may be better to do just error.stackFrames, 
the new object/number/string lazy stack-trace reflection. We can model 
it on the union of error.stack implementations in the field, so those 
could be reimplemented under/on-top-of error.stackFrames. But we'll have 
no compatibility problems to sort out, and fewer complaints about the 
string-valued property (it may be fine to remain underspecified or 
unspecified).

Your point about not violating "use strict" or elaborating too much is 
good, but I want to push back on one thing: local vars may be a bridge 
too far, especially with optimizing JITs, block-scoped let bindings, 
etc. Making arguments available is easier.

Erik, what do you think?

/be