[v8.x] deps: cherry-pick 09b53ee from upstream V8

[addaleax]

This fixes a failure in the v8.x test suite in CI in debug mode. The test is marked flaky, but CI still shows up red for some reason – let’s fix that by actually adressing the bug :)

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Original commit message:

[api] Make running scripts in AddMessageListener callback work in debug mode

The existance of an `AllowJavascriptExecutionDebugOnly` scope in
`Isolate::ReportPendingMessages()` indicates that the API supports
running arbitrary JS code in a `AddMessageListener` callback.

Currently, this can fail in debug mode: The
`!isolate->external_caught_exception()` condition is checked when
entering API methods inside such a handler. However, if there is
a verbose `TryCatch` active when the exception occurs, this
check fails, and when calling `ToString()` on the exception object
leaves a pending exception itself, the flag is re-set to `true`.

Fix this problem by clearing the flag and the pending exception if
there was one during `ToString()`. This matches the code a few lines
up in `messages.cc`, so the exception state is now consistent
during the callback.

This currently makes a Node.js test fail in debug mode
(`parallel/test-error-reporting`).

Bug: node:7144
Bug: node:17016
Change-Id: I060d00fea3e9a497f4df34c6ff8d6e29ebe96321
Reviewed-on: https://chromium-review.googlesource.com/718096
Commit-Queue: Yang Guo <[email protected]>
Reviewed-by: Yang Guo <[email protected]>
Cr-Commit-Position: refs/heads/master@{#49466}

Refs: v8/v8@09b53ee

[nodejs-github-bot]

@addaleax build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/251/pipeline

[MylesBorins]

LGTM

[MylesBorins]

landed in 873ee2e