deps: cherry-pick 804a693 from upstream V8

Original commit message:

    [postmortem] add JS_ERROR_TYPE and context embedder index

      * JS_ERROR_TYPE is required for postmortem tools to inspect
        JSError objects (see https://github.com/nodejs/llnode/pull/215
        for a usage example)
      * The context embedder index is required for postmortem tools to
        access embedder data stored in the context (see
        https://github.com/nodejs/llnode/pull/204 for a usage example)

    R=bmeurer@google.com, yangguo@google.com

    Change-Id: Ib7c7eb44f6ad327fc71a1d45f510c49377db7a25
    Reviewed-on: https://chromium-review.googlesource.com/1138493


Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
    Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#54475}

Refs: https://github.com/v8/v8/commit/804a693eb4ac2fed160c683d16444a53b5

PR-URL: https://github.com/nodejs/node/pull/21855


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Yang Guo <yangguo@chromium.org>