Ditz issue update
Doc updates for internal _tracedata
Make 'tracedata' an internal property

The tracedata contains function references to functions in the current
call stack.  If these functions are not accessible from a sandboxed
environment (through the global object), sandboxed code may gain access
to functions it's not intended to have access to.
Release note: make tracedata internal
Merge branch 'make-tracedata-internal'

Make the `tracedata` property of error objects an internal property to
make sandboxing easier.  Tracedata contains function references to functions
in the current call stack, which may be problematic in some sandboxing
environments: sandboxed code may more easily gain access to functions not
explicitly exposed to it through the sandboxed global object.