This reverts commit e9750cb8.

Reason for revert: Several GC failures, e.g. https://build.chromium.org/p/client.v8/builders/V8%20Linux/builds/23236, https://build.chromium.org/p/client.v8/builders/V8%20Mac/builds/18390 

Original change's description:
> Preempt ConcurrentMarking tasks instead of merely pausing in PauseScope.
> 
> Follow-up to https://chromium-review.googlesource.com/c/v8/v8/+/924867
> 
> This is the core goal of the initial CL @
> https://chromium-review.googlesource.com/c/v8/v8/+/922103
> which was since split into multiple to diagnose a bots-only failure.
> 
> Bug: chromium:812178
> Change-Id: I4c4e0b517737e020862917bd89fa6ce38244e597
> Reviewed-on: https://chromium-review.googlesource.com/924031
> Commit-Queue: Gabriel Charette <gab@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#51356}

TBR=gab@chromium.org,ulan@chromium.org,mlippautz@chromium.org

Change-Id: Ic095e32708e58acbe5955bf29e65af34c59d321e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:812178
Reviewed-on: https://chromium-review.googlesource.com/925301Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51363}

This reverts commit 8b53b9d9.

Reason for revert: Several GC failures, e.g. https://build.chromium.org/p/client.v8/builders/V8%20Linux/builds/23236, https://build.chromium.org/p/client.v8/builders/V8%20Mac/builds/18390 

Original change's description:
> Preempt ConcurrentMarking tasks ASAP when cancelling marking.
> 
> Follow-up to https://chromium-review.googlesource.com/c/v8/v8/+/924867
> 
> Bug: chromium:812178
> Change-Id: I2abe28c6e953df42cffdcbd7ea35df9d29849905
> Reviewed-on: https://chromium-review.googlesource.com/924030
> Commit-Queue: Gabriel Charette <gab@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#51357}

TBR=gab@chromium.org,ulan@chromium.org,mlippautz@chromium.org

Change-Id: Ic4e226fdd02d8259244cef46e9923c95e6606cc4
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:812178
Reviewed-on: https://chromium-review.googlesource.com/924425Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51362}

This extends the previously introduced logic for implementing await
without having to allocate the throwaway promise and the additional
closures and context, to also cover await and yield inside of async
generators.

Bug: v8:7253
Change-Id: I011583a7714bbd148c54e5f204e2076630008db0
Reviewed-on: https://chromium-review.googlesource.com/924003
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51361}

Bug: chromium:811842
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I72163abf0b20b123fb541fe0a1b168e036ef044e
Reviewed-on: https://chromium-review.googlesource.com/919063
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Alexei Filippov <alph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51360}

Change-Id: Id616646bbeebe91e3e575d40799f01611a57643f
Reviewed-on: https://chromium-review.googlesource.com/924281Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51359}

This adds PersistentBase::AnnotateStrongRetainer(const char*) function.

The annotation is used by the heap snapshot generator to show the edges
from the (Global handles) root to the global handles.

Bug: chromium:811842
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I1a9e3e53a53aeaf2b590709fab8dd4ecf7e8f252
Reviewed-on: https://chromium-review.googlesource.com/916788
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Alexei Filippov <alph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51358}

Follow-up to https://chromium-review.googlesource.com/c/v8/v8/+/924867

Bug: chromium:812178
Change-Id: I2abe28c6e953df42cffdcbd7ea35df9d29849905
Reviewed-on: https://chromium-review.googlesource.com/924030
Commit-Queue: Gabriel Charette <gab@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51357}

Follow-up to https://chromium-review.googlesource.com/c/v8/v8/+/924867

This is the core goal of the initial CL @
https://chromium-review.googlesource.com/c/v8/v8/+/922103
which was since split into multiple to diagnose a bots-only failure.

Bug: chromium:812178
Change-Id: I4c4e0b517737e020862917bd89fa6ce38244e597
Reviewed-on: https://chromium-review.googlesource.com/924031
Commit-Queue: Gabriel Charette <gab@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51356}

Change-Id: I101cd4eea87f17a1454c3e2b39c421e304509e61
Reviewed-on: https://chromium-review.googlesource.com/919085
Commit-Queue: Ivica Bogosavljevic <ivica.bogosavljevic@mips.com>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51355}

This will let us identify in traces whether unwinding after receiving
the preemption event is slower than desired and should be optimized.

Adding it to pausing while working on removing it in
https://chromium-review.googlesource.com/c/v8/v8/+/922103
will allow gathering traces that highlight the issue.

R=mlippautz@chromium.org

Bug: chromium:812178
Change-Id: I0555c6825e0792769c9ae2d748d7cc35df4f6fed
Reviewed-on: https://chromium-review.googlesource.com/924122
Commit-Queue: Gabriel Charette <gab@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51354}

This was extracted from https://chromium-review.googlesource.com/c/v8/v8/+/924073/10
after it became clear that using COMPLETE_TASKS/PREEMPT_TASKS where
it should make sense to doesn't work in practice for now.

Experimental CLs which led to the above conclusion:
 - https://chromium-review.googlesource.com/c/v8/v8/+/924865
   (COMPLETE or CANCEL -- still broken)
 - https://chromium-review.googlesource.com/c/v8/v8/+/924866
   (CANCEL only, as before, works)
 - https://chromium-review.googlesource.com/c/v8/v8/+/924028
   (CANCEL and PREEMPT -- broken as well)

Introducing this unittested API allows to reduce the size
of the CLs causing hard-to-diagnose bots-only failures
and fix them individually follow-ups @

 1) https://chromium-review.googlesource.com/c/v8/v8/+/924029
 2) https://chromium-review.googlesource.com/c/v8/v8/+/924031
 3) https://chromium-review.googlesource.com/c/v8/v8/+/924030

Bug: chromium:812178
Change-Id: Icdac456e9f7874b0c4b321ccdb8898297dad7d73
Reviewed-on: https://chromium-review.googlesource.com/924867
Commit-Queue: Gabriel Charette <gab@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51353}

This is a reland of dda0419e.

Originally reviewed-on: https://chromium-review.googlesource.com/914513
and landed as refs/heads/master@{#51342}.

Bug: v8:6791
Change-Id: I3b3a069da7a0e64c38a81b3110dc5ece4887cb19
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/924665Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51352}

Use tools/node/update_node.py instead.

TBR=machenbach@chromium.org

Change-Id: Ib6f7b93e92b27e967627517a0afe2fedd533f6c4
Reviewed-on: https://chromium-review.googlesource.com/924153Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51351}

This replaces three passes over the roots with a single pass.
This also removes root synchronization logic.

The GC subroot index is computed from the |root| parameter of the visit
method. The new |description| parameter is used as an edge name.

Bug: chromium:811842
Change-Id: I03a9215d56b54b3eb5f7bc8b32d5b22ad091c68b
Reviewed-on: https://chromium-review.googlesource.com/916781Reviewed-by: Alexei Filippov <alph@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51350}

This was extracted from https://chromium-review.googlesource.com/c/v8/v8/+/924073/7
in an attempt to isolate hard-to-diagnose bots-only failures there.

Bug: chromium:812178
Change-Id: I980b25ec7d775b74ade75e9166806740b93eea8e
Reviewed-on: https://chromium-review.googlesource.com/924026Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51349}

This is an attempt to isolate what's causing the hard-to-diagnose bots only
failures with that CL.

Bug: chromium:812178
Change-Id: I50ffe8953bebbbc6b5a5e2f689718662a537acb4
Reviewed-on: https://chromium-review.googlesource.com/924864Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51348}

Bug: chromium:810176
Change-Id: I089a1678dfbe0c3bb664e54818a6853f66d364b2
Reviewed-on: https://chromium-review.googlesource.com/923387
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51347}

Change-Id: I4f1d3bd609c48a8deed04e3e59ef326c0e4735c3
Reviewed-on: https://chromium-review.googlesource.com/923985Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51346}

TBR=sergiyb@chromium.org

No-Try: true
Bug: chromium:616879
Change-Id: I5023040d3ce7753d39345033f91848e4f0ed36d9
Reviewed-on: https://chromium-review.googlesource.com/921101
Commit-Queue: Sergiy Byelozyorov <sergiyb@chromium.org>
Reviewed-by: Sergiy Byelozyorov <sergiyb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51345}

This reverts commit dda0419e.

Reason for revert: msvc unhappy:
https://build.chromium.org/p/client.v8/builders/V8%20Win64%20-%20msvc/builds/1434

Original change's description:
> [bigint] Add BigInt64Array, BigUint64Array
> 
> Bug: v8:6791
> Tbr: hpayer@chromium.org
> Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
> Change-Id: I637e9084d2fe4869ad0be2fb996149ab9940f346
> Reviewed-on: https://chromium-review.googlesource.com/914513
> Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
> Reviewed-by: Georg Neis <neis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#51342}

TBR=jkummerow@chromium.org,neis@chromium.org,hpayer@chromium.org

Change-Id: I49237fa323f0d3ea70e744d92d5cbdd4d5c4b39f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6791
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/924663Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51344}

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/c5c828a..e2c6aae

Rolling v8/buildtools: https://chromium.googlesource.com/chromium/buildtools/+log/a09e064..2888931

Rolling v8/third_party/catapult: https://chromium.googlesource.com/catapult/+log/e7298f3..4aa92ef

TBR=machenbach@chromium.org,hablich@chromium.org,sergiyb@chromium.org

Change-Id: Id6e6a5be6a6c2480a83489b2c5f82d8f7139c4b3
Reviewed-on: https://chromium-review.googlesource.com/924357Reviewed-by: v8 autoroll <v8-autoroll@chromium.org>
Commit-Queue: v8 autoroll <v8-autoroll@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51343}

Bug: v8:6791
Tbr: hpayer@chromium.org
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I637e9084d2fe4869ad0be2fb996149ab9940f346
Reviewed-on: https://chromium-review.googlesource.com/914513
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51342}

Depends on: https://crrev.com/c/924114

TBR=yangguo@chromium.org

Bug: chromium:756691
Change-Id: Ibbc3bd35e8727296c1539edc961e3184830575ff
Reviewed-on: https://chromium-review.googlesource.com/924609Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51341}

- Replaces calls to Allocator Reserve, Free, and SetPermissions
  with equivalent page allocator calls (allocation.h).
- Un-implements these methods to catch usage, in preparation for
  removing these.

Bug: chromium:799573
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: Id233b7a9cfc8e332c64e514f6359e8b670c2d75e
Reviewed-on: https://chromium-review.googlesource.com/911883
Commit-Queue: Bill Budge <bbudge@chromium.org>
Reviewed-by: Eric Holk <eholk@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51340}

Intent to ship:
https://groups.google.com/d/msg/v8-users/YZnlGa8ZMoc/_w7H3x_BAgAJ

Bug: v8:7418
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: I9e80dd98fa7b04fee3be591282e455f5576eeed2
Reviewed-on: https://chromium-review.googlesource.com/923728Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Mathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51339}

Bug: chromium:799573
Change-Id: I467c74b5b26bc6f1e1a35c1104df12b77f072bac
Reviewed-on: https://chromium-review.googlesource.com/923430Reviewed-by: Eric Holk <eholk@chromium.org>
Commit-Queue: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51338}

We already cleanup these scripts on frontend side. It is crucial to
cleanup them on backend side as well, since some web applications use
following logic: get some data from network, add this data to buffer,
try to parse buffer using JSON.parse. On each unsuccessfull JSON.parse
we get another scriptFailedToParse event.

Frontend logic of discarding scripts: https://goo.gl/FDtaWK

Some idea of smarter logic here: track what script ids are reported
using protocol and cleanup only script ids which reported not only as
part of scriptFailedToParse event.

R=alph@chromium.org

Bug: chromium:810812
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ifd67764c232e4abc7dc6e8e69a651bf9ac0e381b
Reviewed-on: https://chromium-review.googlesource.com/919834
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Alexei Filippov <alph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51337}

NOTRY=true

Bug: v8:7455
Change-Id: Icb82e8196bc16b4c8b0eebb3c5820e6b3d581735
Reviewed-on: https://chromium-review.googlesource.com/924309Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51336}

This will enable some fuzzers to alter the thread-pool size.

Bug: v8:7455
Change-Id: Ic9c9600cdb3dc50e860dbda8432a23bb20f1dd44
Reviewed-on: https://chromium-review.googlesource.com/924273Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51335}

The ES2017 specification contains a so-called "throwaway" promise that
is used to specify the behavior of await in terms of PerformPromiseThen,
but it's actually not necessary and never exposed to user code. In
addition to that, hooking up the promise in await required a context (to
refer to the generator object) and two closures for the reject/fulfill
handling, which would resume the generator corresponding to the async
function. That meant, we had to allocate 4 additional objects for every
await.

Instead of using a JSPromise plus the callbacks, this CL adds logic to
allow PromiseReaction and PromiseReactionJobTask to carry arbitrary
payloads and Code handlers. We use this for await to avoid the
additional 4 objects mentioned above, and instead just have simple Code
handlers that resume the generator (for the async function), either by
throwing (in case of a rejection) or by resuming normally (in case of
fulfillment).

For this to work properly the JSGeneratorObject has to have a link to
the outer promise returned by the async function, so that the catch
prediction can still figure out what to do in case of promise rejection.
This is done by adding a new generator_outer_promise_symbol when the
debugger is active, which refers from the generator to the outer
promise.

With this change the doxbee-async-es2017-native test goes from around
100.54ms to around 82.45ms, which corresponds to a ~18% reduction in
execution time.

Bug: v8:7253
Change-Id: Iae25b3300bac351c3417be5ae687eff469b0e61f
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/924069Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51334}

Bug: chromium:810176
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I330fa0bdf81d0bb926cf6db794736e89c069f8f2
Reviewed-on: https://chromium-review.googlesource.com/907707Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Commit-Queue: Erik Luo <luoe@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51333}

Add TurboFan inlining support for the following V8 Extras:

 - v8.createPromise
 - v8.rejectPromise
 - v8.resolvePromise

These are used by the streams implementation in Chrome currently, and
were previously not inlined into TurboFan, although TurboFan already
had all the necessary functionality (namely the JSCreatePromise,
JSRejectPromise and JSResolvePromise operators). We might eventually
want to use these functions in Node core as well (at least short-term
for Node 10), to replace the C++ internal API functions with the same
name that are currently being used by parts of Node core.

For this to work, the rejectPromise and resolvePromise builtins had
to be moved back to CSA, as for JavaScript builtins we still have the
policy that the optimizing compiler must not inline them. But that's
straight-forward since the CSA has all the necessary functionality
available anyways.

Bug: v8:7253
Change-Id: I39ab015c379956cd58ace866e17f8ec23b2257b2
Reviewed-on: https://chromium-review.googlesource.com/924146Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51332}

TBR=sergiyb@chromium.org

No-Try: true
Bug: chromium:616879
Change-Id: Id0de15718308b3ed5d5c47be6959513b9a95dc34
Reviewed-on: https://chromium-review.googlesource.com/916762
Commit-Queue: Sergiy Byelozyorov <sergiyb@chromium.org>
Reviewed-by: Sergiy Byelozyorov <sergiyb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51331}

This flag is the WebAssembly native heap equivalent to
FLAG_write_protect_code_memory.

R=mstarzinger@chromium.org

Bug: v8:7454
Change-Id: Id4f671af2e8676d08599c8c30ce03b00e9d33780
Reviewed-on: https://chromium-review.googlesource.com/924071
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51330}

Drive-by-fixes:
- brief print prototype

Bug: v8:7310
Change-Id: I4df82bd76c05ff48a5860bd14cf7711140c0b062
Reviewed-on: https://chromium-review.googlesource.com/923737
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51329}

Bug: v8:7310
Change-Id: I13cc97aa138ad95248e1d366bd0d326cbe1a090e
Reviewed-on: https://chromium-review.googlesource.com/923736Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51328}

Change-Id: Idf3a38c0750071263c6450a17d311cbab632523c
Reviewed-on: https://chromium-review.googlesource.com/924141Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51327}

Will be needed in a follow-up (the constants cache builder needs to
grow arrays in old space).

Bug: v8:6666
Change-Id: Ibd911ffd30e2b0f43881e649b5601111d23e4509
Reviewed-on: https://chromium-review.googlesource.com/924068Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51326}

This flag will be used to toggle things for isolate-independent
builtins during development.

Bug: v8:6666
Change-Id: I8a97f08b3d677a01a2a55a4c6445e71e74471f51
Reviewed-on: https://chromium-review.googlesource.com/924067
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51325}

Bug: v8:7310
Change-Id: I82e7ada4c0f7e415887a859719eb01bb45fd3012
Reviewed-on: https://chromium-review.googlesource.com/921742Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51324}