The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/209824cacd1c20ff8ca17d679fcad59855bc493c

commit 209824cacd1c20ff8ca17d679fcad59855bc493c
Author: Domenic Denicola <domenic@chromium.org>
Date: Sat Jan 05 00:17:05 2019

Async local storage: remove has() and make undefined = not present

Follows https://github.com/domenic/async-local-storage/commit/5bf31109f37d1371f619ea33d0e2391f10e8b8f5, and includes web platform test updates.

Bug:  918704 
Change-Id: Ibc99816d10dba457194ff9e651ead9fc07bd6537
Reviewed-on: https://chromium-review.googlesource.com/c/1393704
Reviewed-by: Hiroshige Hayashizaki <hiroshige@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Commit-Queue: Domenic Denicola <domenic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#620120}
[modify] https://crrev.com/209824cacd1c20ff8ca17d679fcad59855bc493c/third_party/blink/renderer/core/script/resources/layered_api/async-local-storage/index.js
[modify] https://crrev.com/209824cacd1c20ff8ca17d679fcad59855bc493c/third_party/blink/web_tests/external/wpt/async-local-storage/api-surface.tentative.https.html
[modify] https://crrev.com/209824cacd1c20ff8ca17d679fcad59855bc493c/third_party/blink/web_tests/external/wpt/async-local-storage/helpers/als-tests.js
[modify] https://crrev.com/209824cacd1c20ff8ca17d679fcad59855bc493c/third_party/blink/web_tests/external/wpt/async-local-storage/key-types.tentative.https.html
[add] https://crrev.com/209824cacd1c20ff8ca17d679fcad59855bc493c/third_party/blink/web_tests/external/wpt/async-local-storage/undefined-value.https.html