This is just a rebased version of
https://chromium-review.googlesource.com/c/v8/v8/+/571453 with
no functional changes

Bug: v8:6889
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: Ia082cc09ca527505b288ac88e68e0b74eae94765
Reviewed-on: https://chromium-review.googlesource.com/849423Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50417}

This reverts commit d0651bd1.

Reason for revert: Breaks gc stress with embedded snapshot:
https://build.chromium.org/p/client.v8/builders/V8%20Linux64%20GC%20Stress%20-%20custom%20snapshot/builds/15355

Original change's description:
> [language] Implement optional catch binding proposal
> 
> This allows the syntax `try {} catch {}` (with no binding after the
> `catch`).
> 
> See https://github.com/michaelficarra/optional-catch-binding-proposal/
> 
> Currently behind --harmony-optional-catch-binding.
> 
> As part of the implementation, this allows TryCatchStatements to not
> have an associated catch scope; various paths which assumed they
> would have been updated to handle this case.
> 
> Cq-Include-Trybots: master.tryserver.v8:v8_linux_noi18n_rel_ng
> Change-Id: Ic525b45199eef025eb05da562e10fbd4f3d7465f
> Reviewed-on: https://chromium-review.googlesource.com/571453
> Reviewed-by: Marja Hölttä <marja@chromium.org>
> Reviewed-by: Adam Klein <adamk@chromium.org>
> Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Commit-Queue: Kevin Gibbons <bakkot@gmail.com>
> Cr-Commit-Position: refs/heads/master@{#48300}

TBR=rmcilroy@chromium.org,adamk@chromium.org,marja@chromium.org,gsathya@chromium.org,bakkot@gmail.com

Change-Id: I63d68160ec75b87e28d3dcdddca2d8b7d0503b46
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Cq-Include-Trybots: master.tryserver.v8:v8_linux_noi18n_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/702334Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48303}

This allows the syntax `try {} catch {}` (with no binding after the
`catch`).

See https://github.com/michaelficarra/optional-catch-binding-proposal/

Currently behind --harmony-optional-catch-binding.

As part of the implementation, this allows TryCatchStatements to not
have an associated catch scope; various paths which assumed they
would have been updated to handle this case.

Cq-Include-Trybots: master.tryserver.v8:v8_linux_noi18n_rel_ng
Change-Id: Ic525b45199eef025eb05da562e10fbd4f3d7465f
Reviewed-on: https://chromium-review.googlesource.com/571453Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Kevin Gibbons <bakkot@gmail.com>
Cr-Commit-Position: refs/heads/master@{#48300}