Give better stack traces for `PromiseRejectionHandledWarning`
and `UnhandledPromiseRejectionWarning`s.
For `PromiseRejectionHandledWarning`, when it is likely that there
is an `Error` object generated, it is created early to provide a
proper stack trace.
For `UnhandledPromiseRejectionWarning`, the stack trace of the
underlying error object is used, if possible.
Fixes: https://github.com/nodejs/node/issues/9523
PR-URL: https://github.com/nodejs/node/pull/9525
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Anna Henningsen