deps: cherry-pick 68e89fb from v8's upstream

[indutny]

Original commit message:

This commit adds some postmortem data that is otherwise unavailable.

I have discovered need in those values when writing:

https://github.com/indutny/llnode

BUG=

Review URL: https://codereview.chromium.org/1436473002

Cr-Commit-Position: refs/heads/master@{#31947}

This postmortem information is useful for both object inspection, and
function's context variables inspection.

cc @nodejs/v8

@nodejs/release I will be more than happy if it will land in as much versions as possible. It is not really a new feature, as I can always polyfill this in my tools.