The goal is to roll in my upstream patch [1] which speeds up some of the
slowest tests. The impact is especially noticeable on the builder named
“V8 Linux - arm64 - sim - debug”.

Before [2]:

08:57:047 test262/built-ins/RegExp/CharacterClassEscapes/character-class-non-digit-class-escape-flags-u *
08:56:265 test262/built-ins/RegExp/CharacterClassEscapes/character-class-non-word-class-escape-flags-u *
08:53:736 test262/built-ins/RegExp/CharacterClassEscapes/character-class-non-whitespace-class-escape-flags-u *
08:26:101 test262/built-ins/RegExp/CharacterClassEscapes/character-class-non-whitespace-class-escape-flags-u *
06:57:767 test262/built-ins/RegExp/CharacterClassEscapes/character-class-non-word-class-escape-flags-u *
05:04:746 test262/built-ins/RegExp/CharacterClassEscapes/character-class-non-digit-class-escape-flags-u *
01:46:609 test262/built-ins/Array/prototype/filter/15.4.4.20-9-c-ii-1 *
[…other unrelated tests…]

After [3]:

01:46:630 test262/built-ins/Array/prototype/filter/15.4.4.20-9-c-ii-1 *
[…other unrelated tests…]

That is, tests that previously took almost 9 minutes to run now don’t even
show up in the list of slowest tests anymore.

[1] https://github.com/tc39/test262/pull/1927
[2] https://logs.chromium.org/logs/v8/buildbucket/cr-buildbucket.appspot.com/8930575270954225344/+/steps/Test262_-_no_variants/0/logs/durations/0
[3] https://logs.chromium.org/logs/v8/buildbucket/cr-buildbucket.appspot.com/8930489323837575408/+/steps/Test262_-_no_variants/0/logs/durations/0

Bug: v8:7834
Change-Id: I1d0cea3b64223f7b0ec89c46235632855b8c7eee
Reviewed-on: https://chromium-review.googlesource.com/c/1323733Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Mathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57332}