toString for error stack

Right now as far as I can tell the stack is a very informative javascript object whereas in native exceptions - it is a string.

I think it will be a good idea to add some presets for toStringing stack, so it is easier to look at and display etc.

If you think it is a good idea too I can try to comeup with some solution.

The issue names no files, entry points, or tests. Start by locating where TraceKit exposes its stack object, then compare that representation with native JavaScript exception stack strings. The work is complete when the desired string presets are defined, implemented, and verified against the expected display format.

Written by the indexing model from the issue text.