This is a JavaScript fuzzer originally authored by Oliver Chang. It
is a mutation based fuzzer using Babel code transformations. For more
information see the included README.md.

The original code was altered:
- Add new V8 copyright headers.
- Make the test expectation generator aware of the headers.
- Fix file endings for presubmit checks.
- Fix `npm test` on fresh checkout with a new fake DB.
- Make test skipping work with new v8/tools location.
- OWNERS file.
- New title section in README.md.

No-Try: true
Bug: chromium:1109770
Change-Id: Ie71752c0a37491a50500c49060a3c526716ef933
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2320330
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69164}

Excluded regions are no longer available to the RegionAllocator, so
should not be freeable so actually enforce that and aAdd a test.

Bug: v8:10454
Change-Id: I51c41cf0bf3d2eeb699b10b1fa02f5465d93b6aa
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2330026Reviewed-by: Igor Sheludko (OOO Aug 3-17) <ishell@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69163}

This reverts commit 13141c8a.

Reason for revert: https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20UBSan/12253?

Original change's description:
> [zone-compr] Introduce ZoneTypeTraits and ZoneCompression
> 
> Also move zone compression flags to src/common/globals.h.
> 
> Bug: v8:9923
> Change-Id: Id0a77720e735e2669a1e5eef48e1b4866ad99480
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2324255
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Commit-Queue: Igor Sheludko <ishell@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#69160}

TBR=leszeks@chromium.org,ishell@chromium.org

Change-Id: I01fc05b33d01c19f9a9432d4b2dd73cf8b38b972
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9923
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2332163Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69162}

If we are near the stack limit, calling the proxy method might not work
any more. Instead of crashing because of an empty MaybeLocal, handle
this gracefully.

Drive-by: Minor refactoring in TryGetValue.

R=tebbi@chromium.org

Bug: chromium:1110001
Change-Id: I07e7773768166b3dbea2e6b75a3ab8b24bfeee53
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2332156Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69161}

Also move zone compression flags to src/common/globals.h.

Bug: v8:9923
Change-Id: Id0a77720e735e2669a1e5eef48e1b4866ad99480
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2324255Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69160}

R=clemensb@chromium.org

Bug: chromium:1111015
Change-Id: Ia56e38e1aa1b7de69b2203fe2b028f24cba16861
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2330024
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69159}

The shutdown process should destroy AccountingAllocator instance before
the V8 platform.

Bug: v8:9923
Change-Id: Iff76b64d16c42c711ce4ee0c3533acd5ba5aaaa5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2330020Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69158}

* GetThreadSlot was missing const (Blink CL failed to build).
* Aligning IsEmptyThreadSafe implementation with IsEmpty.

Bug: chromium:1108537
Change-Id: I9c07e9a0e7f029cf3d70b4d2507900b600d064cc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2330027
Auto-Submit: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69157}

This normative PR reached consensus in the July 2020 TC39:
https://github.com/tc39/ecma262/pull/2057

Bug: v8:10768
Change-Id: Ibe2affea0447b923435f77de5d3c0233deeb9877
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2327753
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69156}

https://chromium.googlesource.com/external/github.com/tc39/test262/+log/8575a6eb1..0f5a274aad

Bug: v8:7834
Change-Id: Ie5fb4b4682f50d3c35d03b15a24b2680d4ecd175
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2327964
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69155}

This adds new methods AllocateSharedPages, ReserveForSharedMemoryMapping
and CanAllocateSharedPages to v8::PageAllocator, which if overridden
allows the platform to declare that it supports allocation and remapping
of shared memory.

This interface is currently a work in progress so the new methods are
marked "INTERNAL ONLY" and they may change without being first
deprecated.

An implementation of PageAllocator is provided that can allocate and map
shared memory on Linux and Android, but no other platforms are yet
supported. While Windows is not supported the interface has been
designed to make this possible as AllocateSharedPages returns a
SharedMemory object that wraps the shared memory and provides its own
remap function. This should allow the SharedMemory object on windows to
contain a mapping a to hFileMappingObject as required by
MapViewOfFileEx.

Bug: v8:10454
Change-Id: I2e601d49ea14da44867a102c823fa4e341cf0dab
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2306789Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69154}

This is a reland of 482c3bbf

Original change's description:
> [Intl] Sync Intl.Segmenter to latest version
> 
> https://tc39.es/proposal-intl-segmenter/
> 
> TC39 passed Intl.Segmenter to stage 3 in Jul 21.
> This CL move our earlier prototype to the current spec.
> 
> Bug: v8:6891
> Change-Id: I07234beed54f671c26bdbfb3983c5bc2fa5a29b0
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2219413
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Reviewed-by: Frank Tang <ftang@chromium.org>
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Commit-Queue: Frank Tang <ftang@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#69080}

Bug: v8:6891
Change-Id: Ie3a02d8ddf6f95f0632f97b38b613b185abeb592
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2321118Reviewed-by: Frank Tang <ftang@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69153}

The resolvedOptions of Intl.NumberFormat depends on the ICU's
skeleton. sffc change the output of the wildcard from + to *
in ICU67
(https://github.com/unicode-org/icu/commit/ac4540f8a45775ba1aafdb352e2561c0d1527329)

Change the v8 code to use * instead.

Bug: chromium:1108810
Change-Id: I8b0249a5bc4cc199f454c5070635100f68d1f48d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2318272Reviewed-by: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69152}

This was previously running on TurboFan and scalar lowering. Since
Liftoff has gained support for shuffle instructions, we can run it
there too.

Bug: v8:10696
Change-Id: I5a33d500b8e584ec4d6ffd29373593aabebae4b6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2327183
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69151}

Change all the callers in backend specific instruction-selector
to call the functions in simd-shuffle.h

Also copy over the documentation that was in instruction-selector.h
to simd-shuffle.h.

Bug: v8:10696
Change-Id: Ic9339d6481316f18c19f35c45460e700b45ec38e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2327182
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69150}

These are no longer tied to instruction-selector, so move them out into
their own unittests. We can then remove the *ForTesting methods.

Bug: v8:10696
Change-Id: I387cf38290d9602b011ee1d13ee5285ac660f208
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2326951Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69149}

This is a spec bug in V8. Only call expressions literally of the form
'eval(...)' are considered direct.

Bug: v8:10688
Change-Id: Ia5ac9992db82cad0ad6870119bd94a0b4daee417
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2327752Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69148}

This reverts commit 5ee39a50.

Reason for revert: To trigger builders again

Original change's description:
> Whitespace to trigger builders
> 
> TBR: clemensb@chromium.org
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Change-Id: Id8dba0dad4b7bfd68ed7c0300ddfeac2b9c349b2
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2330012
> Reviewed-by: Liviu Rau <liviurau@chromium.org>
> Commit-Queue: Liviu Rau <liviurau@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#69146}

TBR=clemensb@chromium.org,liviurau@chromium.org

Change-Id: Iff68a4ab57a30bdc594a49f3ff0cff43740b6634
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2330015Reviewed-by: Liviu Rau <liviurau@chromium.org>
Commit-Queue: Liviu Rau <liviurau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69147}

TBR: clemensb@chromium.org
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: Id8dba0dad4b7bfd68ed7c0300ddfeac2b9c349b2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2330012Reviewed-by: Liviu Rau <liviurau@chromium.org>
Commit-Queue: Liviu Rau <liviurau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69146}

Bug: v8:9891
Change-Id: Ief289a9990ac545aa479f564094e3bbde4144aae
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2293709
Commit-Queue: Gus Caplan <snek@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69145}

... by ensuring that the V8 platform is initialized before the
AccountingAllocator used in the tests.

Bug: v8:9923
Change-Id: I2d75b7c26dab55b9258c1be800a37a6f777f1103
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2328791Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69144}

This is to group them up and not have classes and methods intertwined.

Change-Id: I8147f06f060932f7b70e478324ce5868d0ffd5d4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2328786Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69143}

Bug: chromium:1108537
Change-Id: I82a64d57432b7e0854a3787f309c85477d37f701
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2327910Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69142}

Adds unittests that test the fast register allocator correctly deals
with spills of Phi's between their definition and a predecessor block's
gap move to populate the Phi.

BUG=v8:9684

Change-Id: I17263058d5ac29088895ad3de7b3131315ec8fae
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2299371
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69141}

Due to dynamic map checks we generate different code and the pattern
fails. As a note, the other tests have already been disabled for
TurboProp.

Bug: v8:9684, v8:9820
Change-Id: Ib8be11ae10bc801116d6a17d1c6b08d8026287b3
Fixes: v8:9820
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2328784
Auto-Submit: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69140}

Adds support for Phis to be allocated to the fast register
allocator. Registers used for Phis are marked specially between
the point where the Phi is defined, and the gap-move's in the
predecessor blocks which populate the Phi value, since if the
Phi is spilled then all predecessor blocks must also spill the
Phi even if they were already allocated.

BUG=v8:9684

Change-Id: Iebe90495b83df655d3335a7d55874123f3b27f8d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2299366
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69139}

PersistentHandlesScope works similar to the DeferredHandleScope, but
returns PersistentHandles instead of DeferredHandles on Detach().

Since PersistentHandlesScope takes over filled blocks from the
main thread local handle, remove the block_size_ field and use
kHandleBlockSize instead. This way all blocks have exactly the same size.

Bug: v8:10315
Change-Id: I295cad6f84852f87c55d95572905069443f5698c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2324254
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69138}

The DecompressionOptimizationPhase performs MachineRepresentation
changes in the nodes, which causes the node's instruction selection
to avoid decompression.

It is safe to run after we already have a schedule since it does not
drop any nodes.

Bug: v8:9684, v8:7703
Change-Id: I636ae80fa82d0c78878756e9f39e7a14c02803b0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2324252
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69137}

Bug: v8:10477
Change-Id: I0ce6cd46d3886a37e96bdd62df263addc5b9631f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2327186Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69136}

lvx and stvx require 16-byte aligned addresses.
This CL enables loading and storing to addresses which are not
16-byte aligned.

Change-Id: I5635e857a979520822c8b30bb5477a159e97e6e5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2327648Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#69135}

This reverts commit 76b53b66.

Reason for revert: Can't be used easily in embedder (Chromium).

Original change's description:
> [api] Add a SharedArrayBuffersEnabled callback.
> 
> - Adds a SharedArrayBuffersEnabled callback and uses it to
>   enable/disable SABs per context. The feature flag is used
>   if no callback is registered.
> 
> Bug: chromium:923807
> Change-Id: I4d3472fcd79b158cb50dc98793aece6dbbb81d93
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2316901
> Reviewed-by: Adam Klein <adamk@chromium.org>
> Commit-Queue: Bill Budge <bbudge@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#69057}

TBR=bbudge@chromium.org,adamk@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: chromium:923807
Change-Id: I6e3ddfa9cd64ba3106b4a75ea7a5185f873facc9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2326952Reviewed-by: Bill Budge <bbudge@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69134}

Although the code generator already combines return instructions late
in the pipeline into a common site, there were still superfluous jumps
to that common site left in the code.

Change-Id: I06c885fb0ab6a2c078f9dabdc6616c6881f42c75
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2284984
Commit-Queue: Daniel Clifford <danno@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69133}

This prints a message whenever we discard compiled metadata of an SFI.
The message identifies the SFI. I've found this helpful when debugging.

Change-Id: Ib34266199ade2ef88a6bafe32295ab505ce7c899
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2324260Reviewed-by: Mythri Alle <mythria@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Auto-Submit: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69132}

Temporarily disable cctest DisasmPoisonMonomorphicLoadFloat64.

Bug: v8:9820
Change-Id: I3208a7f85aa7ab2c09602107b2f0954f02b15a45
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2326332Reviewed-by: Santiago Aboy Solanes <solanes@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Auto-Submit: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69131}

I noticed that, with pointer-compression enabled, in map checks we no
longer load the map as part of the cmp instruction:

movl rcx,[rdx-0x1]
movl rdi,0x8286f8d  ;; (compressed) object: <Map(HOLEY_ELEMENTS)>
cmpl rdi,rcx

This CL restores that:

movl rcx,0x82c6f8d  ;; (compressed) object: <Map(HOLEY_ELEMENTS)>
cmpl [rdx-0x1],rcx

Change-Id: Ifcc7f34fddf6aa423c0a26066ac124e9757cb9ab
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2320653Reviewed-by: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69130}

The bug was that the allocation of the result array (before the loop)
was using the outer frame state, thus returning the allocation's result
(an array full of holes) as the return value of the map operation in
case the allocation triggers a lazy deopt.

Bug: chromium:1104514
Change-Id: I9a6db8a5860472e1b438b6b54414938d61e166c1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2324249Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69129}

Bug: v8:10582, v8:9684
Change-Id: Ib29e9b56d4c722cb572e86def7eeb3f588dc9c2d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2316079Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69128}

Since we now add the additional required capacity when assessing
StringTable shrinking during LookupKey-caused string insertion, we no
longer have to add a slack capacity. This more closely matches previous
behaviour, which didn't consider the additional required capacity but
did add slack (which, because of rounding to the next power of two,
amounts to the same thing).

Bug: chromium:1108258
Change-Id: I81f513fdc800a2caab76e030c0c5e767cd1360d1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2324253
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69127}

If we don't have slack and we want to add an element to the
TransitionArray, we would create a new TransitionArray. The background
hread, however, can be holding a pointer to the old transitions. This
test tests that this is safe to do, i.e the background thread reading
the old TransitionArray.

To make sure that we are testing that, we can add more synchronization
via an extra semaphore.

Bug: v8:7790
Change-Id: Ie454d79282ac267d3527269e8490baced979aa45
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2323351Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69126}

This CL aims to clean dead code across the app
and use private class fields for storing private
information.

Bug: v8:10644, v8:10735

Change-Id: I1129104925f230bed922cc76abdb432d536d2111
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2323352Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Commit-Queue: Zeynep Cankara <zcankara@google.com>
Cr-Commit-Position: refs/heads/master@{#69125}