This patch gives the ability for the embedder to ask for the
module requests of a module, and to pass a ResolveCallback
into Module::Instantiate().
In d8, I've implemented a simple module_map that's used
along with this API to allow loading, compiling, instantiating,
and evaluating a whole tree of modules.
No path resolution is yet implemented, meaning that all
import paths are relative to whatever directory d8 runs
in. And no imports are linked to the exports of the
requested module.
BUG=v8:1569
Review-Url: https://codereview.chromium.org/2351113004
Cr-Commit-Position: refs/heads/master@{#39569}
Reason for revert:
Unblocking roll
Original issue's description:
> [d8] Fix the shared-library build
>
> This commit ensures that the d8 shared library build uses the same logic as
> the standard static build by exporting relevant functions and classes.
>
> BUG=chromium:646337
>
> Committed: https://crrev.com/2c10ca8086a4d595ecf9aa843d2031b068470d65
> Cr-Commit-Position: refs/heads/master@{#39503}
TBR=jochen@chromium.org,vogelheim@chromium.org,bmeurer@chromium.org,titzer@chromium.org,jgruber@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:646337
Review-Url: https://codereview.chromium.org/2356703003
Cr-Commit-Position: refs/heads/master@{#39526}
Introduce TraceStateObserver interface along with add/remove
methods to the platform.
BUG=chromium:406277
Review-Url: https://codereview.chromium.org/2344893005
Cr-Commit-Position: refs/heads/master@{#39513}
This commit ensures that the d8 shared library build uses the same logic as
the standard static build by exporting relevant functions and classes.
BUG=chromium:646337
Review-Url: https://codereview.chromium.org/2342563002
Cr-Commit-Position: refs/heads/master@{#39503}
Rename JSModule to Module and make it a Struct rather than a JSObject. We will
later add a separate JSModuleNamespace object to implement the 'import * as foo'
syntax.
BUG=v8:1569
Review-Url: https://codereview.chromium.org/2345823002
Cr-Commit-Position: refs/heads/master@{#39477}
This exposes an interface for the embedder to provide a delegate which can
serialize or deserialize embedder-specific objects, like Blink's DOM wrappers.
BUG=chromium:148757
Review-Url: https://codereview.chromium.org/2327653002
Cr-Commit-Position: refs/heads/master@{#39422}
GetFunctionNameStr and GetScriptResourceNameStr can be called from a thread
other than isolate VM thread unlike their conterparts GetFunctionName
and GetScriptResourceName.
BUG=406277
Review-Url: https://codereview.chromium.org/2328673003
Cr-Commit-Position: refs/heads/master@{#39313}
The existing PropertyQueryCallback intercepts getOwnPropertyDescriptor, but
it returns only value and attributes, not the accessors. This
PropertyDescriptorCallback returns a descriptor similar to Ecma-262 6.2.4.
You can either set a PropertyQueryCallback or a PropertyDescriptorCallback,
but not both. When you set a callback for DefineProperty(), you can set a
PropertyDescriptorCallback but not a PropertyQueryCallback.
BUG=v8:5359
Review-Url: https://codereview.chromium.org/2311873002
Cr-Commit-Position: refs/heads/master@{#39279}
- inspector becomes a dependency of v8_base;
- generated public protocol files are placed to gen/v8/include/inspector/<Domain.h>;
- added v8_enable_inspector_override to be used in embedders (gn only);
- combined public headers into v8-inspector.h and v8-inspector-protocol.h.
BUG=chromium:635948
Review-Url: https://codereview.chromium.org/2292053003
Cr-Commit-Position: refs/heads/master@{#39226}
This restores the contract that all API methods that return Maybe<T> or
MaybeLocal<T> always throw an exception when they return nothing.
Since v8::ValueDeserializer::ReadHeader can now throw exceptions, it
needs a Local<Context> parameter so that it can set up execution state
(entering the context, etc.). The old method has been marked for
deprecation, but since this API is experimental I intend to remove it
as soon as I've removed the use from Blink.
value-serializer-unittest has been updated to expect an exception in
all decode failure cases.
BUG=chromium:148757,chromium:641964
Review-Url: https://codereview.chromium.org/2308053002
Cr-Commit-Position: refs/heads/master@{#39188}
With the Indexed/GenericNamedPropertyDefinerCallback it is possible to intercept Object.defineProperty() calls.
Requests that call JSReceiver::OrdinaryDefineOwnProperty() internally, also trigger the interceptor. This includes Object.freeze(), Object.preventExtensions(), and Object.seal().
As without this patch, the query interceptor triggers on
defineProperty, unless the definer callback
intercepts the request.
As without this patch, the query interceptor triggers on defineProperty, unless the definer callback intercepts the request.
BUG=
Committed: https://crrev.com/b9d985975cf3bab0ded0cec9fafd3799f9bde29a
Review-Url: https://codereview.chromium.org/2272383002
Cr-Original-Commit-Position: refs/heads/master@{#39094}
Cr-Commit-Position: refs/heads/master@{#39122}
Reason for revert:
Breaks cctest/test-api-interceptors/QueryInterceptor on the waterfall
Original issue's description:
> [api] Add interceptor for defineProperty().
>
> With the Indexed/GenericNamedPropertyDefinerCallback it is possible to intercept Object.defineProperty() calls.
>
> Requests that call JSReceiver::OrdinaryDefineOwnProperty() internally, also trigger the interceptor. This includes Object.freeze(), Object.preventExtensions(), and Object.seal().
>
> BUG=
>
> Committed: https://crrev.com/b9d985975cf3bab0ded0cec9fafd3799f9bde29a
> Cr-Commit-Position: refs/heads/master@{#39094}
TBR=jochen@chromium.org,franzih@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=
Review-Url: https://codereview.chromium.org/2303533004
Cr-Commit-Position: refs/heads/master@{#39095}
With the Indexed/GenericNamedPropertyDefinerCallback it is possible to intercept Object.defineProperty() calls.
Requests that call JSReceiver::OrdinaryDefineOwnProperty() internally, also trigger the interceptor. This includes Object.freeze(), Object.preventExtensions(), and Object.seal().
BUG=
Review-Url: https://codereview.chromium.org/2272383002
Cr-Commit-Position: refs/heads/master@{#39094}
Also add tests that document the behavior of the PropertyQueryCallback.
BUG=v8:5260
Review-Url: https://codereview.chromium.org/2286323002
Cr-Commit-Position: refs/heads/master@{#39090}
The comment for the Proxy::New functions seems inaccurate and is
currently identical to Map::New:
3090 /**
3091 * Creates a new empty Map.
3092 */
3093 static Local<Map> New(Isolate* isolate);
This commit updates the comment to describe that it creates a Proxy and
not a Map.
BUG=
Review-Url: https://codereview.chromium.org/2176063002
Cr-Commit-Position: refs/heads/master@{#39002}
V8 can use this metter to better estimate the amount of work that is still to be
done by the embedder. Supposed to be used to decide whether incremental marking
should be finalized or not.
BUG=chromium:468240
R=ulan@chromium.org
Review-Url: https://codereview.chromium.org/2291613002
Cr-Commit-Position: refs/heads/master@{#38985}
Add comments to make it easier to browse the HTML documentation generated with Doxygen.
BUG=v8:5260
Review-Url: https://codereview.chromium.org/2290553003
Cr-Commit-Position: refs/heads/master@{#38982}
The embedder is expected to arrange for the array buffer contents to be
transferred into a v8::ArrayBuffer in the receiving context (generally by
assuming ownership of the externalized backing store).
BUG=chromium:148757
Review-Url: https://codereview.chromium.org/2275033003
Cr-Commit-Position: refs/heads/master@{#38948}
Suitably scary warnings attached, as this will yet evolve (notably to handle
host objects, which are not currently handled).
Unit tests adjusted to use the public version of ValueSerializer, eliminating
any need they have to access v8::internal.
With this, Blink can begin using this code experimentally behind a flag as it
develops.
BUG=chromium:148757
Review-Url: https://codereview.chromium.org/2274693002
Cr-Commit-Position: refs/heads/master@{#38915}
According to our style guide on Copyable and Movable Types,
copy/move operators should be disabled using = delete in the public: section.
Use consistent style for disabling new and delete.
BUG=
Review-Url: https://codereview.chromium.org/2276063002
Cr-Commit-Position: refs/heads/master@{#38880}
According to our style guide on Copyable and Movable Types,
copy/move operators should be disabled using = delete in the public: section,
not in the private: section.
BUG=
Review-Url: https://codereview.chromium.org/2272063002
Cr-Commit-Position: refs/heads/master@{#38879}
According to our style guide on Copyable and Movable Types,
copy/move operators should be disabled in the public: section, not
in the private: section.
BUG=
Review-Url: https://codereview.chromium.org/2278573002
Cr-Commit-Position: refs/heads/master@{#38872}
This flag was shipped on in 52, so it's due for removal. The patch includes
removing the deprecated and unused-in-Blink API Promise::Chain, and many
test updates.
R=adamk@chromium.org
BUG=v8:4633
Review-Url: https://codereview.chromium.org/2267033002
Cr-Commit-Position: refs/heads/master@{#38804}
Reason for revert:
Tanks octane
Original issue's description:
> [heap] Improve size profiling for ArrayBuffer tracking
>
> Eagerly account for retained sizes during ArrayBuffer tracking. Following up on this,
> we can now do Scavenges if the amount of memory retained from new space is too large.
>
> BUG=chromium:621829
> R=jochen@chromium.org,hpayer@chromium.org
>
> Committed: https://crrev.com/28e13bd6a75c9467dae43043e7b741a1387d5252
> Cr-Commit-Position: refs/heads/master@{#38731}
TBR=jochen@chromium.org,hpayer@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:621829
Review-Url: https://codereview.chromium.org/2261513003
Cr-Commit-Position: refs/heads/master@{#38739}
Eagerly account for retained sizes during ArrayBuffer tracking. Following up on this,
we can now do Scavenges if the amount of memory retained from new space is too large.
BUG=chromium:621829
R=jochen@chromium.org,hpayer@chromium.org
Review-Url: https://codereview.chromium.org/2210263002
Cr-Commit-Position: refs/heads/master@{#38731}
Reason for revert:
Performance regressions in Gameboy, Life, CodeLoad and others. See crbug.com/638210.
Original issue's description:
> Refactor data structures for simple stack traces
>
> Simple stack traces are captured through Isolate::CaptureSimpleStackTrace.
> Captured frames are stored in a FixedArray, which in turn is stored as a
> property (using a private symbol) on the error object itself. Actual formatting
> of the textual stack trace is done lazily when the user reads the stack
> property of the error object.
>
> This would involve many conversions back and forth between index-encoded raw
> data (receiver, function, offset and code), JS CallSite objects, and C++
> CallSite objects.
>
> This commit refactors the C++ CallSite class into a Struct class called
> StackTraceFrame, which is the new single point of truth frame information.
> Isolate::CaptureSimpleStackTrace stores an array of StackTraceFrames, and JS
> CallSite objects (now created only when the user specifies custom stack trace
> formatting through Error.prepareStackTrace) internally only store a reference
> to a StackTraceFrame.
>
> BUG=
>
> Committed: https://crrev.com/b4c1aefb9c369f1a33a6ca94a5de9b06ea4bf5c4
> Cr-Commit-Position: refs/heads/master@{#38645}
TBR=yangguo@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=
Review-Url: https://codereview.chromium.org/2252783007
Cr-Commit-Position: refs/heads/master@{#38700}
Simple stack traces are captured through Isolate::CaptureSimpleStackTrace.
Captured frames are stored in a FixedArray, which in turn is stored as a
property (using a private symbol) on the error object itself. Actual formatting
of the textual stack trace is done lazily when the user reads the stack
property of the error object.
This would involve many conversions back and forth between index-encoded raw
data (receiver, function, offset and code), JS CallSite objects, and C++
CallSite objects.
This commit refactors the C++ CallSite class into a Struct class called
StackTraceFrame, which is the new single point of truth frame information.
Isolate::CaptureSimpleStackTrace stores an array of StackTraceFrames, and JS
CallSite objects (now created only when the user specifies custom stack trace
formatting through Error.prepareStackTrace) internally only store a reference
to a StackTraceFrame.
BUG=
Review-Url: https://codereview.chromium.org/2230953002
Cr-Commit-Position: refs/heads/master@{#38645}
A test exercising the public APIs for wasm serialization and
simulates the serialization scenario - serialize in one isolate, deserialize
in another.
BUG=v8:5072
Review-Url: https://codereview.chromium.org/2249973002
Cr-Commit-Position: refs/heads/master@{#38644}
This patch is based on alph's CL https://codereview.chromium.org/2128613004/.
This patch makes GetStackSample propogate the register state when using
simulator helper, and adds argument to avoid using register state from simulator
when pass the native register state.
BUG=v8:4789
LOG=N
Review-Url: https://codereview.chromium.org/2189513002
Cr-Commit-Position: refs/heads/master@{#38554}
LoadInternalField performs some redundant checks in the context of
fast accessors.
This improves the speedup from 20% to 60% for next/previousSibling in
the Dromaeo DOM traversal benchmarks.
BUG=chromium:508898
Review-Url: https://codereview.chromium.org/2186593002
Cr-Commit-Position: refs/heads/master@{#38535}
We only need these external v8 APIs to expose serialization externally,
so bypassed having an internal layer for now.
BUG=v8:5072
Review-Url: https://codereview.chromium.org/2228073002
Cr-Commit-Position: refs/heads/master@{#38516}
Drive-by-fix: mark isolates as const in stack-allocated scopes
BUG=chromium:630217
Review-Url: https://codereview.chromium.org/2220993003
Cr-Commit-Position: refs/heads/master@{#38496}
This new API function allows for setting several internal fields at once.
By avoiding crossing the API each time for setting an internal property we
can speed up the wrapper creation which has to set two fields for every new
object.
BUG=chromium:630217
Review-Url: https://codereview.chromium.org/2185963002
Cr-Commit-Position: refs/heads/master@{#38299}
The client can use scriptId + lineNumber + columnNumber
to uniquelly identify the call site.
Review-Url: https://codereview.chromium.org/2199003003
Cr-Commit-Position: refs/heads/master@{#38236}
Add deps file allowing libplatform.h to include v8-tracing.h.
Additionally removes redundant include/ that was causing build errors
for node-lkgr.
BUG=
Review-Url: https://codereview.chromium.org/2195403002
Cr-Commit-Position: refs/heads/master@{#38217}
Reason for revert:
Revert this CL due to V8 Arm Builder failure and V8 Mips Builder failure.
https://build.chromium.org/p/client.v8.ports/builders/V8%20Arm%20-%20builder/builds/2456https://build.chromium.org/p/client.v8.ports/builders/V8%20Mips%20-%20builder/builds/2506
Original issue's description:
> [Tracing] V8 Tracing Controller
>
> V8 has had a trace event macro interface for while, but without a tracing
> controller a standalone V8 would be unable to collect traces.
>
> This CL introduces a complete Tracing Controller system for V8.
> It is fully function except that it does not yet store trace event args.
>
> This CL has a few components,
> The tracing controller itself, contributed by the author of this CL
> The Trace config (including the parser), contributed by lpy@
> The Trace Object, Trace Writer, and Trace Buffer are all contributed by rksang@
>
> BUG=v8:4561
> LOG=N
>
> Committed: https://crrev.com/3d598452679ce208ad9b2f48e0fb3fae352ce375
> Cr-Commit-Position: refs/heads/master@{#38073}
TBR=jochen@chromium.org,mattloring@google.com,rskang@google.com,yangguo@chromium.org,fmeawad@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4561
Review-Url: https://codereview.chromium.org/2183943002
Cr-Commit-Position: refs/heads/master@{#38074}
V8 has had a trace event macro interface for while, but without a tracing
controller a standalone V8 would be unable to collect traces.
This CL introduces a complete Tracing Controller system for V8.
It is fully function except that it does not yet store trace event args.
This CL has a few components,
The tracing controller itself, contributed by the author of this CL
The Trace config (including the parser), contributed by lpy@
The Trace Object, Trace Writer, and Trace Buffer are all contributed by rksang@
BUG=v8:4561
LOG=N
Review-Url: https://codereview.chromium.org/2137013006
Cr-Commit-Position: refs/heads/master@{#38073}
Introduce a proper CodeStubAssembler::BranchIfToBooleanIsTrue helper
method, that branches to if_true/if_false labels depending on whether
the value that is passed would yield true or false when fed to
ToBoolean. Use this helper to implement the bytecode handlers w/o having
to materialize the temporary booleans and essentially branching twice.
The CodeStubAssembler::BranchIfToBooleanIsTrue helper favors the most
likely case of a Boolean constant now.
Also migrate the ToBooleanStub to a ToBoolean TurboFan builtin, that
also uses the helper method under the hood.
Remove the now obsolete Oddball::to_boolean field.
R=hpayer@chromium.org, rmcilroy@chromium.org, yangguo@chromium.org
Review-Url: https://codereview.chromium.org/2151163002
Cr-Commit-Position: refs/heads/master@{#37849}
Original issue's description:
> Don't compile functions in a context the caller doesn't have access to
>
> Instead just return undefined
>
> A side effect of this is that it's no longer possible to compile
> functions in a detached context.
>
> BUG=chromium:541703
> R=verwaest@chromium.org,bmeurer@chromium.org
BUG=chromium:541703
R=verwaest@chromium.org
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng
Review-Url: https://codereview.chromium.org/2155503004
Cr-Commit-Position: refs/heads/master@{#37842}
When reading through the source code (v8.h) I found some minor typos
which I wanted to report.
BUG=
Review-Url: https://codereview.chromium.org/2130513002
Cr-Commit-Position: refs/heads/master@{#37835}
Reason for revert:
blink is unhappy about the microtask change
Original issue's description:
> Reland "Don't compile functions in a context the caller doesn't have access to"
>
> Original issue's description:
> > Don't compile functions in a context the caller doesn't have access to
> >
> > Instead just return undefined
> >
> > A side effect of this is that it's no longer possible to compile
> > functions in a detached context.
> >
> > BUG=chromium:541703
> > R=verwaest@chromium.org,bmeurer@chromium.org
>
> BUG=chromium:541703
> R=verwaest@chromium.org
>
> Committed: https://crrev.com/6bceabac5b705b2ce1f52d34650cea1ae3b8c617
> Cr-Commit-Position: refs/heads/master@{#37756}
TBR=verwaest@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:541703
Review-Url: https://codereview.chromium.org/2151843002
Cr-Commit-Position: refs/heads/master@{#37760}
Original issue's description:
> Don't compile functions in a context the caller doesn't have access to
>
> Instead just return undefined
>
> A side effect of this is that it's no longer possible to compile
> functions in a detached context.
>
> BUG=chromium:541703
> R=verwaest@chromium.org,bmeurer@chromium.org
BUG=chromium:541703
R=verwaest@chromium.org
Review-Url: https://codereview.chromium.org/2143893005
Cr-Commit-Position: refs/heads/master@{#37756}
Currently the code example in the FunctionTemplate class documentation
is out of date. This commit updates the examples so they compile and run
without error.
BUG=
Review-Url: https://codereview.chromium.org/2127523003
Cr-Commit-Position: refs/heads/master@{#37741}
Reason for revert:
Causes crashes on Canary
Original issue's description:
> Don't compile functions in a context the caller doesn't have access to
>
> Instead just return undefined
>
> A side effect of this is that it's no longer possible to compile
> functions in a detached context.
>
> BUG=chromium:541703
> R=verwaest@chromium.org,bmeurer@chromium.org
> CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng
>
> Committed: https://crrev.com/992e34c21635b179a993b82ac1d81753e7a6a57a
> Cr-Commit-Position: refs/heads/master@{#37657}
TBR=bmeurer@chromium.org,verwaest@chromium.org,jochen@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=chromium:541703, chromium:628053
Review-Url: https://codereview.chromium.org/2148163002
Cr-Commit-Position: refs/heads/master@{#37736}
Instead just return undefined
A side effect of this is that it's no longer possible to compile
functions in a detached context.
BUG=chromium:541703
R=verwaest@chromium.org,bmeurer@chromium.org
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng
Review-Url: https://codereview.chromium.org/2034083002
Cr-Commit-Position: refs/heads/master@{#37657}
Isolate is not going to retain a CPU profiler.
The client will be creating an instance of profiler when needed.
Deprectate v8::Isolate::GetCpuProfiler()
BUG=v8:4789
Review-Url: https://codereview.chromium.org/2117343006
Cr-Commit-Position: refs/heads/master@{#37613}
Such an object can be used to later create a context from it. It has to
have access checks with handlers enabled, as it cannot be accessed
otherwise.
BUG=chromium:618305
R=verwaest@chromium.org
Review-Url: https://codereview.chromium.org/2107673003
Cr-Commit-Position: refs/heads/master@{#37594}
We want to eventually move the profiling functionality out of V8 as library,
this patch exposes TickSample and its APIs in v8-profiler.h so that when
embedders use library, they can have more details.
Minor change: Rename tick-sample.[h|cc] to simulator-helper.[h|cc].
BUG=v8:4789
LOG=N
Review-Url: https://codereview.chromium.org/2105943002
Cr-Commit-Position: refs/heads/master@{#37564}
This patch implements "immutable prototype exotic objects" from the ECMAScript
spec, which are objects whose __proto__ cannot be changed, but are not otherwise
frozen. They are introduced in order to prevent a Proxy from being introduced
to the prototype chain of the global object.
The API is extended by a SetImmutablePrototype() call in ObjectTemplate, which
can be used to vend new immutable prototype objects. Additionally, Object.prototype
is an immutable prototype object.
In the implementation, a new bit is added to Maps to say whether the prototype is
immutable, which is read by SetPrototype. Map transitions to the immutable prototype
state are not saved in the transition tree because the main use case is just for
the prototype chain of the global object, which there will be only one of per
Context, so no need to take up the extra word for a pointer in each full transition
tree.
BUG=v8:5149
Review-Url: https://codereview.chromium.org/2108203002
Cr-Commit-Position: refs/heads/master@{#37482}
This part of the snapshot API should not be in use yet, so we can still
change this. The motivation for this change is:
- Use MaybeHandle where reasonable.
- Remove ambiguity: when we use index to create context from snapshot,
we should not have a silent fallback if snapshot is not available.
- Symmetry: rename to Context::FromSnapshot to mirror templates.
R=jochen@chromium.org
BUG=chromium:617892
Review-Url: https://codereview.chromium.org/2100073002
Cr-Commit-Position: refs/heads/master@{#37334}
We deviate from spec in that, in our implementation, __defineGetter__ on non-
configurable properties returns false instead of throwing a TypeError. This commit
adds a use counter to track how often we would be throwing an error we currently
avoid, to determine if we can change to align with spec or if the spec is not
implementable.
BUG=v8:5070
Review-Url: https://codereview.chromium.org/2089533002
Cr-Commit-Position: refs/heads/master@{#37259}
Base the fast-path in AdjustAmountOfExternalMemory on a value + limit. To
preserve the behavior the limit is just set using kExternalAllocationLimit.
Redo naming of related members.
R=jochen@chromium.org
BUG=chromium:621829
LOG=N
Review-Url: https://codereview.chromium.org/2085893002
Cr-Commit-Position: refs/heads/master@{#37131}
I need this method because of ActiveScriptWrappables, which have to be processed
at the atomic pause even for incremental solution, as there is no other way of
detecting when an object starts or stops being active than querying it.
LOG=no
BUG=468240
Review-Url: https://codereview.chromium.org/2065833003
Cr-Commit-Position: refs/heads/master@{#37062}
With cl https://codereview.chromium.org/2043033002 blink will add new wrappers
to its marking deque (and maintain this deque) so black allocated wrappers are
not a problem anymore. To limit the scope of when blink has to detect wrappers,
we need to tell blink when we start and when we end full gcs. For that we can
nicely use TracePrologue and TraceEpilogue.
LOG=no
BUG=468240
Review-Url: https://codereview.chromium.org/2051103002
Cr-Commit-Position: refs/heads/master@{#36937}
