Add support, as compatible as we can, for Error class extensions
from the V8 script engine:

* RhinoException.useV8StackStyle(boolean)
  This causes stack traces to be formatted like V8 does.

* Error.captureStackTrace(err) (JavaScript)
  This causes a stack trace to be generated at the current point, and
  added to the object "err" as a property named "stack".

* Error.prepareStackTrace(err, stack) (JavaScript)
  This function is called whenever the stack trace is generated,
  and may return something to be used instead of the default
  stack trace. An array of "CallSite" objects are passed. These
  are as compatible as V8 as we can make them, which is to say that the
  only functions that work are "getFileName", "getFunctionName", and
  "getLineNumber".

Docs for the API are found here:
https://code.google.com/p/v8/wiki/JavaScriptStackTraceApi