When a stack trace is captured, it is stored in a private symbol on
the respective Error object. The first access to "Error.stack"  will
then format the stack trace, with a possible call into user JS via
the Error.prepareStackTrace callback.

Until now, the accessor converted ".stack" to a normal data
property containing the formatted stack trace. This causes a new Map
with a new DescriptorArray to be created, which will not be shared
with anything else (also not other error objects with formated
stack traces).

This CL changes the accessor to store the formatted stack trace in
the same symbol (stack_trace_symbol) as the structured data. The
result is that an error object will have the same Map before and
after "Error.stack" is accessed.

Bug: v8:9115
Change-Id: I7d6bf49be76d63b57fbbaf904cc6ed7dbdbfb96b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1564061
Commit-Queue: Simon Zünd <szuend@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60865}