Regression range points to b590679496e829fd2f88ba4494072f0196c979de, still reproduces with tip-of-tree as of today, hence I believe this is _not_ a pure dupe of  issue 778574 .

danno: Uh oh! This issue still open and hasn't been updated in the last 14 days. This is a serious vulnerability, and we want to ensure that there's progress. Could you please leave an update with the current status and any potential blockers?

If you're not the right owner for this issue, could you please remove yourself as soon as possible or help us find the right one?

If the issue is fixed or you can't reproduce it, please close the bug. If you've started working on a fix, please set the status to Started.

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The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/d5885ca2b9b65769dfad9d55c21eb52b99f0071f

commit d5885ca2b9b65769dfad9d55c21eb52b99f0071f
Author: Daniel Clifford <danno@chromium.org>
Date: Fri Nov 10 15:23:28 2017

Fix splice bug in handling of negative arguments length

Bug:  chromium:778668 
Change-Id: Ie75f2ecb9e6134b6eb57c7d7fb6ea33cbb2fc2bf
Reviewed-on: https://chromium-review.googlesource.com/753324
Commit-Queue: Daniel Clifford <danno@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49301}
[modify] https://crrev.com/d5885ca2b9b65769dfad9d55c21eb52b99f0071f/src/builtins/builtins-array-gen.cc
[add] https://crrev.com/d5885ca2b9b65769dfad9d55c21eb52b99f0071f/test/mjsunit/regress/regress-778668.js

This is a serious security regression. If you are not able to fix this quickly, please revert the change that introduced it.

If this doesn't affect a release branch, or has not been properly classified for severity, please update the Security_Impact or Security_Severity labels, and remove the ReleaseBlock label. To disable this altogether, apply ReleaseBlock-NA.

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 Issue 779803  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/4002bf96e3ae9f3bb7c18009d34faa7980a61f85

commit 4002bf96e3ae9f3bb7c18009d34faa7980a61f85
Author: Daniel Clifford <danno@chromium.org>
Date: Thu Nov 16 12:17:58 2017

Fix hole escape in dictionary mode Array.prototype.slice()

Bug:  chromium:778668 
Change-Id: I0d2cc2166aab93bb7cb5dcc6c72cdb0b335a655f
Reviewed-on: https://chromium-review.googlesource.com/774263
Commit-Queue: Daniel Clifford <danno@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49410}
[modify] https://crrev.com/4002bf96e3ae9f3bb7c18009d34faa7980a61f85/src/elements.cc
[modify] https://crrev.com/4002bf96e3ae9f3bb7c18009d34faa7980a61f85/src/objects.cc
[add] https://crrev.com/4002bf96e3ae9f3bb7c18009d34faa7980a61f85/test/mjsunit/regress/regress-784863.js

This bug has been closed for more than 14 weeks. Removing security view restrictions.

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