This CL also adds hydrogen stubs for global loads and global stores, full-codegen and TurboFan now uses this machinery.
Review URL: https://codereview.chromium.org/1224793002
Cr-Commit-Position: refs/heads/master@{#29592}
Note that there are currently no objects that require a pre-allocated
properties backing store, all such slots are in-object properties from
the begining. Hence {unused + pre_allocated - inobject == 0} holds.
R=verwaest@chromium.org
Review URL: https://codereview.chromium.org/1226203011
Cr-Commit-Position: refs/heads/master@{#29590}
Reduce Float64 comparison to Float32 when both inputs are conversions from
Float32.
Review URL: https://codereview.chromium.org/1235663002
Cr-Commit-Position: refs/heads/master@{#29586}
For now it uses a pretty slow path for accessing strings by wrapping it into a new temporary wrapper.
BUG=v8:4042, v8:3088
LOG=y
Review URL: https://codereview.chromium.org/1221303019
Cr-Commit-Position: refs/heads/master@{#29576}
EnumtSet has been deprecated for quite some time, and replaced with the
more general and type safe base::Flags template class.
R=jarin@chromium.org
Review URL: https://codereview.chromium.org/1229233002
Cr-Commit-Position: refs/heads/master@{#29564}
Break point at calls are currently set via IC. To change this, we
need to set debug break slots instead. We also need to distinguish
those debug break slots as calls to support step-in.
To implement this, we add a data field to debug break reloc info to
indicate non-call debug breaks or in case of call debug breaks, the
number of arguments. We can later use this to find the callee on the
evaluation stack in Debug::PrepareStep.
BUG=v8:4269
R=ulan@chromium.org
LOG=N
Review URL: https://codereview.chromium.org/1222093007
Cr-Commit-Position: refs/heads/master@{#29561}
When running without a snapshot, the GlobalEval function gets lazy compiled.
By the time we compile it, its name is "eval", which causes the parser to
choke (functions named "eval" aren't allowed in strict mode!).
Instead, we now always skip checking the function name when lazy-parsing,
as the name has already been checked appropriately by the preparser.
Also cleaned up other cases that don't require name checking by introducing
FunctionNameValidity enum and passing appropriate values throughout the
parser and preparser.
This lets us pass an additional 18 test262 tests.
BUG=v8:4198
LOG=n
Review URL: https://codereview.chromium.org/1227093005
Cr-Commit-Position: refs/heads/master@{#29559}
Instead of updating the SharedFuntionInfo set the name property on
the function directly.
BUG=v8:4278
LOG=N
R=verwaest@chromium.org, littledan@chromium.org
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel
Review URL: https://codereview.chromium.org/1227523003
Cr-Commit-Position: refs/heads/master@{#29558}
When quit() is called, d8 shell exits without cleanup. If a worker is running,
it might be holding the context_mutex_, which if destroyed will DCHECK.
BUG=4279
R=jarin@chromium.org
LOG=n
Review URL: https://codereview.chromium.org/1231473002
Cr-Commit-Position: refs/heads/master@{#29557}
The function returned from Function.prototype.bind should have the same
[[Prototype]] as the receiver.
BUG=v8:3889
LOG=N
R=adamk@chromium.org, verwaest@chromium.org
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel
Review URL: https://codereview.chromium.org/1217603005
Cr-Commit-Position: refs/heads/master@{#29556}
This basically means that we must not use the b(Label*) version here,
but the b(int) version instead to jump over the constant pool.
BUG=v8:4292
LOG=y
Review URL: https://codereview.chromium.org/1224243002
Cr-Commit-Position: refs/heads/master@{#29552}
The b, bl and blx methods that take labels basically ignore the constant
pool check and just block the constant pool for the next instruction.
This way a long enough sequence of those instructions will block can
potentially block the constant pool emission for too long.
BUG=v8:4292
LOG=y
R=yangguo@chromium.org
Review URL: https://codereview.chromium.org/1223093004
Cr-Commit-Position: refs/heads/master@{#29550}
The breakage to Chrome seems to be based on @@isConcatSpreadable
and turning that part off with this patch fixes the Maps Tips & Tricks
test case.
BUG=chromium:507553
LOG=Y
R=adamk
Review URL: https://codereview.chromium.org/1226063002
Cr-Commit-Position: refs/heads/master@{#29545}
Optimize string "length" property access based on static type
information if possible, but also optimistically optimize the access
based on type feedback from the LoadIC.
R=jarin@chromium.org
Review URL: https://codereview.chromium.org/1216593003
Cr-Commit-Position: refs/heads/master@{#29543}
This one occurred when serializing an object. When the property getter threw an
exception, that value was skipped, but the property count wasn't updated. The
deserializer then tried to deserialize the wrong value.
BUG=chromium:506549
R=jarin@chromium.org
LOG=n
Review URL: https://codereview.chromium.org/1220193004
Cr-Commit-Position: refs/heads/master@{#29541}
- Add a TurboFanIC class, derived from TurboFanCodeStub, that
automatically distinguishes between versions of the IC called from
optimized and unoptimized code.
- Add appropriate InterfaceDescriptors for both the versions of the
stub called from unoptimized and optimized code
- Change the MathFloor TF stub generator to output either the
for-optimized or for-unoptimized version based on the minor_key
parameter.
Committed: https://crrev.com/8f13b655b8a10dae2116dd18b32f09337bb2d410
Cr-Commit-Position: refs/heads/master@{#29534}
Review URL: https://codereview.chromium.org/1225943002
Cr-Commit-Position: refs/heads/master@{#29539}
Reason for revert:
Failure on compiling runtime.js on windows
Original issue's description:
> Add unoptimized/optimized variants of MathFloor TF code stub
>
> - Add a TurboFanIC class, derived from TurboFanCodeStub, that
> automatically distinguishes between versions of the IC called from
> optimized and unoptimized code.
> - Add appropriate InterfaceDescriptors for both the versions of the
> stub called from unoptimized and optimized code
> - Change the MathFloor TF stub generator to output either the
> for-optimized or for-unoptimized version based on the minor_key
> parameter.
>
> Committed: https://crrev.com/8f13b655b8a10dae2116dd18b32f09337bb2d410
> Cr-Commit-Position: refs/heads/master@{#29534}
TBR=mvstanton@chromium.org,bmeurer@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Review URL: https://codereview.chromium.org/1220783006
Cr-Commit-Position: refs/heads/master@{#29535}
- Add a TurboFanIC class, derived from TurboFanCodeStub, that
automatically distinguishes between versions of the IC called from
optimized and unoptimized code.
- Add appropriate InterfaceDescriptors for both the versions of the
stub called from unoptimized and optimized code
- Change the MathFloor TF stub generator to output either the
for-optimized or for-unoptimized version based on the minor_key
parameter.
Review URL: https://codereview.chromium.org/1225943002
Cr-Commit-Position: refs/heads/master@{#29534}
Smi immediates are not supported, so instructions with Smi representations need their constants in a register. LAddI has already been doing this. The manifestation of the bug was that an operation would compute 0 instead of the correct result.
BUG=chromium:478612
LOG=y
R=verwaest@chromium.org
Review URL: https://codereview.chromium.org/1224623017
Cr-Commit-Position: refs/heads/master@{#29529}
We actually need round to zero truncation to implement the counterpart
of LDoubleToI in TurboFan, which tries to convert a double to an integer
as required for keyed load/store optimizations.
Drive-by-cleanup: Reduce some code duplication in the InstructionSelector
implementations.
R=jarin@chromium.org
Review URL: https://codereview.chromium.org/1225993002
Cr-Commit-Position: refs/heads/master@{#29527}
The RawMachineAssembler will be used to build the interpreter, so it needs
to move back to src/compiler.
This reverts commit b5b00cc031.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1221303014
Cr-Commit-Position: refs/heads/master@{#29519}
If we compile handlers to call accessors, Debug::HandleStepIn won't get
called. Therefore we need to clear ICs each time. This has not been
necessary before because we used to patch ICs for breaking, and restored
them with cleared ICs. This is no longer the case. We do not use ICs
for breaking anymore, so they are not implicitly cleared any longer.
R=mvstanton@chromium.org
BUG=v8:4269
LOG=N
Review URL: https://codereview.chromium.org/1212253009
Cr-Commit-Position: refs/heads/master@{#29518}
Reason for revert:
[Sheriff] Test hangs sometimes and times out flakily. E.g.: http://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20nosse3/builds/4551/steps/Check%20%28flakes%29/logs/d8-worker-sharedarray..
Original issue's description:
> Fix bug when transferring SharedArrayBuffer to multiple Workers.
>
> Previously, the serialization code would call Externalize for every transferred
> ArrayBuffer or SharedArrayBuffer, but that function can only be called once. If
> the buffer is already externalized, we should call GetContents instead.
>
> Also fix use-after-free bug when transferring ArrayBuffers. The transferred
> ArrayBuffer must be internalized in the new isolate, or be managed by the
> Shell. The current code gives it to the isolate externalized and frees it
> immediately afterward when the SerializationData object is destroyed.
>
> BUG=chromium:497295
> R=jarin@chromium.org
> LOG=n
>
> Committed: https://crrev.com/dd7962bf7838f8379ba776ee6b7b0e4d3bec2140
> Cr-Commit-Position: refs/heads/master@{#29499}
TBR=jarin@chromium.org,jochen@chromium.org,binji@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:497295
Review URL: https://codereview.chromium.org/1224843008
Cr-Commit-Position: refs/heads/master@{#29506}
Previously, the serialization code would call Externalize for every transferred
ArrayBuffer or SharedArrayBuffer, but that function can only be called once. If
the buffer is already externalized, we should call GetContents instead.
Also fix use-after-free bug when transferring ArrayBuffers. The transferred
ArrayBuffer must be internalized in the new isolate, or be managed by the
Shell. The current code gives it to the isolate externalized and frees it
immediately afterward when the SerializationData object is destroyed.
BUG=chromium:497295
R=jarin@chromium.org
LOG=n
Review URL: https://codereview.chromium.org/1215233004
Cr-Commit-Position: refs/heads/master@{#29499}
Remove the context specialization hack from the AstGraphBuilder, and
properly specialize to the function context in the context specialization.
And replace the correct context in the JSInliner.
R=mstarzinger@chromium.org
BUG=v8:4273
LOG=n
Review URL: https://codereview.chromium.org/1218873005
Cr-Commit-Position: refs/heads/master@{#29493}
We have to reland these two commits at once, because the first breaks
some asm.js benchmarks without the second. The change was reverted
because of bogus checks in the verifier, which will not work in the
presence of OSR (and where hidden because of the type back propagation
hack in OSR so far). Original messages are below:
[turbofan] Add new JSFrameSpecialization reducer.
The JSFrameSpecialization specializes an OSR graph to the current
unoptimized frame on which we will perform the on-stack replacement.
This is used for asm.js functions, where we cannot reuse the OSR
code object anyway because of context specialization, and so we could as
well specialize to the max instead.
It works by replacing all OsrValues in the graph with their values
in the JavaScriptFrame.
The idea is that using this trick we get better performance without
doing the unsound backpropagation of types to OsrValues later. This
is the first step towards fixing OSR for TurboFan.
[turbofan] Perform OSR deconstruction early and remove type propagation.
This way we don't have to deal with dead pre-OSR code in the graph
and risk optimizing the wrong code, especially we don't make
optimistic assumptions in the dead code that leaks into the OSR code
(i.e. deopt guards are in dead code, but the types propagate to OSR
code via the OsrValue type back propagation).
BUG=v8:4273
LOG=n
R=jarin@chromium.org
Review URL: https://codereview.chromium.org/1226673005
Cr-Commit-Position: refs/heads/master@{#29486}
`WriteUtf16Slow` should not assume that the output buffer has enough
bytes to hold both words of surrogate pair. It should pass the number of
remaining bytes to the `Utf8::ValueOf` instead, just as we already do in
`Utf8DecoderBase::Reset`. Otherwise it will attempt to write the trail
uint16_t past the buffer boundary, leading to memory corruption and
possible crash.
Originally reported by: Kris Reeves <kris.re@bbhmedia.com>
BUG=v8:4274
R=danno
R=svenpanne
LOG=y
Review URL: https://codereview.chromium.org/1226493003
Cr-Commit-Position: refs/heads/master@{#29485}
This way we don't have to deal with dead pre-OSR code in the graph and
risk optimizing the wrong code, especially we don't make optimistic
assumptions in the dead code that leaks into the OSR code (i.e. deopt
guards are in dead code, but the types propagate to OSR code via the
OsrValue type back propagation).
BUG=v8:4273
LOG=n
R=jarin@chromium.org
Review URL: https://codereview.chromium.org/1215333005
Cr-Commit-Position: refs/heads/master@{#29478}
The context constant cannot be materialized from the frame when we are
compiling for OSR, because the context spill slot contains the current
instead of the outermost context in full-codegen.
R=bmeurer@chromium.org
Review URL: https://codereview.chromium.org/1220013003
Cr-Commit-Position: refs/heads/master@{#29472}
Currently we lower shifts directly to machine operators, and add an
appropriate Word32And to implement the & 0x1F operation on the right
hand side required by the specification. However for Word32And we assume
Int32 in simplified lowering, which is basically changes the right hand
side bit interpretation for the shifts from Uint32 to Int32, which is
obviously wrong. So now we represent that explicitly by proper
simplified operators for the shifts, which are lowered to machine in
simplified lowering.
R=jarin@chromium.org
Review URL: https://codereview.chromium.org/1213803008
Cr-Commit-Position: refs/heads/master@{#29465}
Keeping this CL separate in case there are more GC-stress problems.
BUG=v8:3956
LOG=N
Review URL: https://codereview.chromium.org/1217543006
Cr-Commit-Position: refs/heads/master@{#29449}
This is an adaptation of test-profile-generator/BailoutReason to when
try-catch statements are optimizable. They will no longer cause any
bailout reason to be reported.
R=yangguo@chromium.org
TEST=cctest/test-profile-generator/BailoutReason
Review URL: https://codereview.chromium.org/1213113007
Cr-Commit-Position: refs/heads/master@{#29440}
The only right way to enable access checks is to install access check callbacks on an object template via v8::ObjectTemplate::SetAccessCheckCallbacks(). It does not make sense to enable access checks on an arbitrary object.
Review URL: https://codereview.chromium.org/1217893012
Cr-Commit-Position: refs/heads/master@{#29439}
This involves:
- Enabling the tail call optimization reducer in all cases.
- Adding an addition flag to CallFunctionParameters to mark call sites
that can be tail-called enabled.
- Only set the tail-call flag for %_CallFunction.
R=bmeurer@chromium.org
Review URL: https://codereview.chromium.org/1216933011
Cr-Commit-Position: refs/heads/master@{#29436}
Support 32-bit cmp with shift/extend by reusing the existing add/sub shift and
extend code.
Review URL: https://codereview.chromium.org/1218103005
Cr-Commit-Position: refs/heads/master@{#29435}
Conditionally including Array and TypedArray methods seems to cause
a slowdown in V8 context creation, possibly due to the new code added.
BUG=chromium:504629
R=adamk@chromium.org
LOG=Y
Review URL: https://codereview.chromium.org/1215863003
Cr-Commit-Position: refs/heads/master@{#29430}
This is more consistent with the DOM API, and is clearer w.r.t. which values
are available in the lexical environment of the Worker.
BUG=chromium:497295
R=jarin@chromium.org
LOG=n
Review URL: https://codereview.chromium.org/1218553004
Cr-Commit-Position: refs/heads/master@{#29426}
Disabling rsqrt and recip for mips32r1 in assembler, disassembler and simulator
Review URL: https://codereview.chromium.org/1221663006
Cr-Commit-Position: refs/heads/master@{#29425}
This change changes bootstrapping semantics for intercepted global objects. Unlike before, we'll now also call into the interceptor during bootstrapping. This affects properties loaded from within the runtime, such as global.Array and global.Symbol. The embedder will need to make sure that those values are the expected values during bootstrapping.
BUG=chromium:505998
LOG=n
Review URL: https://codereview.chromium.org/1220813005
Cr-Commit-Position: refs/heads/master@{#29414}
The enumerable expression in a for-in/of loop is supposed to have a TDZ for any
lexically bound names in that loop (there can be more than one with destructuring).
This patch accomplishes this with an almost-correct desugaring. The only thing missing
is proper debugger support (the let declarations added by the desugaring, while invisible
to code due to shadowing, are visible to the debugger).
BUG=v8:4210
LOG=n
Review URL: https://codereview.chromium.org/1218543003
Cr-Commit-Position: refs/heads/master@{#29396}
v8::Internal::List will DCHECK when indexing out of the array, even if just to
get the address, and the value is never used. So this construct will fail:
memcpy(p, &data[0], length);
When data is empty and length is 0.
BUG=chromium:505778
R=mstarzinger@chromium.org
LOG=n
Review URL: https://codereview.chromium.org/1216853003
Cr-Commit-Position: refs/heads/master@{#29388}
Revert "Revert relanded strong property access CL"
Regression issues should be solved. Initial patchset is the original, subsequent patchsets are the fixing modifications.
This reverts commit 4ac7be5656.
BUG=v8:3956
LOG=N
Review URL: https://codereview.chromium.org/1199983002
Cr-Commit-Position: refs/heads/master@{#29384}
Also fixes a crankshaft bug with strong implicit conversions.
It turns out that the implicit conversion of oddball values
is smushed into so many places in crankshaft that it would
have been pretty invasive surgery to make everything fall
out naturally.
BUG=v8:3956
LOG=N
Review URL: https://codereview.chromium.org/1216463003
Cr-Commit-Position: refs/heads/master@{#29381}
Move the arithmetic shift from Int32MulHigh to a following Int32Add on ARM64.
This graph is commonly generated on reduction of signed integer division.
Review URL: https://codereview.chromium.org/1209413008
Cr-Commit-Position: refs/heads/master@{#29380}
This change makes possible to save and restore the FP registers
in the Prologue and Return parts for the CallAddress kind functions.
TEST=test-simplified-lowering/RunNumberDivide_2_TruncatingToUint32,
test-simplified-lowering/RunNumberMultiply_TruncatingToUint32
Review URL: https://codereview.chromium.org/1191513003
Cr-Commit-Position: refs/heads/master@{#29378}
The deoptimizer (and probably various other places) cannot deal properly
with recursive function inlining, so we disallow it in TurboFan as well.
We might want to reconsider that decision at some point in the future.
R=jarin@chromium.org
Review URL: https://codereview.chromium.org/1211243007
Cr-Commit-Position: refs/heads/master@{#29374}
This has become necessary as we have more experimental natives
that run after deserializing from the snapshot.
R=hpayer@chromium.org
BUG=v8:4200
LOG=N
Review URL: https://codereview.chromium.org/1218973002
Cr-Commit-Position: refs/heads/master@{#29367}
This optimization never triggers currently, and is inherently native
context dependent for no real reason (for example it will not properly
detect those constructors in the case of cross native context inlining),
plus it is slow and awkward. In case we really need this functionality
at some point, we should find a way to make it work with the builtin
function id mechanism that is already in place to match other builtins.
R=jarin@chromium.org,rossberg@chromium.org
Review URL: https://codereview.chromium.org/1221683006
Cr-Commit-Position: refs/heads/master@{#29365}
This makes sure that the exit control flow that merges the try-block
with the catch-block after a try-catch-statement creates a new merge
node in cases where it has to. Otherwise dangling phi nodes might have
the wrong number of value inputs.
R=bmeurer@chromium.org
TEST=mjsunit/regress/regress-crbug-505354
BUG=chromium:505354
LOG=N
Review URL: https://codereview.chromium.org/1213183003
Cr-Commit-Position: refs/heads/master@{#29362}
The failure was been triggered by turning on --harmony-arrays,
maybe because code size was increased or code was added later
in the bootstrap process. Because it doesn't look like a bug
in anything guarded by --harmony-arrays directly, I'd suggest
shipping the flag and disabling the test on the architectures
where it's been observed to fail. It's already disabled on arm64
and this patch disables it on mips64 as well.
BUG=v8:4200
LOG=N
R=adamk
Review URL: https://codereview.chromium.org/1212963004
Cr-Commit-Position: refs/heads/master@{#29361}
This makes new.target work in [[Call]] and [[Construct]] of ordinary
functions.
We achieve this by introducing a new construct stub for functions that
uses the new.target variable. The construct stub pushes the original
constructor just above the receiver in the construct frame.
BUG=v8:3887
LOG=N
R=adamk@chromium.org, dslomov@chromium.org
Review URL: https://codereview.chromium.org/1203813002
Cr-Commit-Position: refs/heads/master@{#29358}
zlib is broken for mips after 35eb3a0260.
We're still working on a fix. Skip test for now, so the bots cycle green.
BUG=
Review URL: https://codereview.chromium.org/1209253005
Cr-Commit-Position: refs/heads/master@{#29356}
Dumb typo introduced in refs/heads/master@{#29306}. I thought I was turning on
report_exceptions in Shell::ExecuteString, but instead I turned on print_result
(which assumes an interactive debugger and a HandleScope for the
utility_context_).
BUG=chromium:504727,chromium:504728
R=mstarzinger@chromium.org
LOG=n
Review URL: https://codereview.chromium.org/1219563002
Cr-Commit-Position: refs/heads/master@{#29350}
The test language/asi/S7.9_A5.7_T1 is failing intermittently.
BUG=v8:4253
LOG=N
TBR=adamk
Review URL: https://codereview.chromium.org/1215813002.
Cr-Commit-Position: refs/heads/master@{#29332}
The use of jalr ra is unpredictable if instruction in branch delay slot
is in next page.
This finally fixes random failures in JS debugger and InteruptRequest tests.
TEST=mjsunit/debug-*,
cctest/test-api/RequestInterruptTestWithNativeAccessor
BUG=
Review URL: https://codereview.chromium.org/1220443002
Cr-Commit-Position: refs/heads/master@{#29331}
Note that prior to having canonical shared function infos, this has
been a source of duplicate shared function infos.
R=bmeurer@chromium.org
BUG=chromium:504787
LOG=N
Review URL: https://codereview.chromium.org/1209383002
Cr-Commit-Position: refs/heads/master@{#29326}
This allows context-independent code generated by TurboFan to be cached
in the optimized code map and reused across native contexts. Note that
currently this cache is still flushed at GC time.
R=bmeurer@chromium.org,mvstanton@chromium.org
TEST=cctest/test-compiler/OptimizedCodeSharing
Review URL: https://codereview.chromium.org/1208013002
Cr-Commit-Position: refs/heads/master@{#29313}
This will enable tail call optimization even across inlining. Plus it
might enable some other interesting optimizations as well. In order to
avoid blowing up the generated code, we can still canonicalize the
epilogue in the CodeGenerator, similar to what fullcodegen does.
R=jarin@chromium.org
Review URL: https://codereview.chromium.org/1215623002
Cr-Commit-Position: refs/heads/master@{#29311}
The issue is that Worker.prototype.terminate was deleting the C++ Worker
object, and then Worker.prototype.getMessage was trying to read messages from
the queue.
The simplest solution is to keep workers in a zombie state when they have been
terminated. They won't be reaped until Shell::CleanupWorkers is called.
I've also fixed some threading issues with Workers:
* Workers can be created by another Worker, so the Shell::workers_ variable
must be protected by a mutex.
* An individual Worker can typically only be accessed by the isolate that
created it, but the main thread can always terminate it, so the Worker::state_
must be accessed in a thread-safe way.
BUG=chromium:504136
R=jochen@chromium.org
LOG=n
Review URL: https://codereview.chromium.org/1208733002
Cr-Commit-Position: refs/heads/master@{#29306}
We need to do the ToName before the ToObject.
BUG=v8:4229
LOG=N
R=adamk
Review URL: https://codereview.chromium.org/1211663002
Cr-Commit-Position: refs/heads/master@{#29272}
If the replacer array contains a number wrapper we should use the
toString result and not valueOf.
BUG=v8:4228
LOG=N
R=adamk
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel
Review URL: https://codereview.chromium.org/1207013002
Cr-Commit-Position: refs/heads/master@{#29270}
The i18n.js code was calling a lot of methods, which might have been
removed or replaced by user code.
Make sure we use the original functions.
BUG=v8:4220
LOG=N
R=adamk, littledan
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel
Review URL: https://codereview.chromium.org/1199813004
Cr-Commit-Position: refs/heads/master@{#29268}
