Revert of Remove support for thread-based recompilation (patchset #1 id:1 of https://codereview.chromium.org/966653002/)

Reason for revert:
speculative revert due to gc-stress timeouts.

Original issue's description:
> Remove support for thread-based recompilation
>
> BUG=v8:3608
> R=yangguo@chromium.org
> LOG=y
>
> Committed: https://crrev.com/ed5db223a19dfe126af012e894582251aa3635d7
> Cr-Commit-Position: refs/heads/master@{#27619}

TBR=jochen@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
BUG=v8:3608
LOG=N

Review URL: https://codereview.chromium.org/1063383004

Cr-Commit-Position: refs/heads/master@{#27654}

NOTRY=true
NOTREECHECKS=true

Review URL: https://codereview.chromium.org/1064043002

Cr-Commit-Position: refs/heads/master@{#27653}

TBR=yangguo@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1067353002

Cr-Commit-Position: refs/heads/master@{#27652}

R=yangguo@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1070663002

Cr-Commit-Position: refs/heads/master@{#27651}

Perhaps we should throw an exception and/or change our external API to
use a MaybeLocal, but that would be a bigger change. For now, we just
return undefined when something goes wrong with the DebugContext,
which is good enough to avoid crashing.

BUG=chromium:474538
LOG=y

Review URL: https://codereview.chromium.org/1065213002

Cr-Commit-Position: refs/heads/master@{#27650}

This is a follow-up to 2d281e71 and prevents bailouts on empty
script contexts in Crankshaft, which don't need allocation. Only
non-empty script contexts should cause a bailout.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/1063373003

Cr-Commit-Position: refs/heads/master@{#27649}

BUG=v8:4015
LOG=n

Review URL: https://codereview.chromium.org/1040603002

Cr-Commit-Position: refs/heads/master@{#27648}

This should have been part of https://codereview.chromium.org/1056863002/. :-/

TBR=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/1070593002

Cr-Commit-Position: refs/heads/master@{#27647}

Performance measurements show that the position independent code is
usually slightly faster than the position dependent code, and there
seems to be no noticable regression.

This also gets rid of a lot of support code that was only required to allow
embedding labels into the code stream. And it implies that neither the GC
nor the deserializer need to do anything for jump tables.

R=svenpanne@chromium.org
BUG=v8:3872
LOG=n

Review URL: https://codereview.chromium.org/1069633002

Cr-Commit-Position: refs/heads/master@{#27646}

Rolling v8/tools/clang to 7ec0c52c7a66cd94c96b8eb37bacd26d152e40e6

TBR=machenbach@chromium.org

Review URL: https://codereview.chromium.org/1070533002

Cr-Commit-Position: refs/heads/master@{#27645}

Port c67cb287

BUG=

Review URL: https://codereview.chromium.org/1061363003

Cr-Commit-Position: refs/heads/master@{#27644}

Port 2d281e71

Original commit message:
This enables eager optimization of top-level code with TurboFan and
extends test coverage by triggering it with the --always-opt flag.
Script contexts are now also properly allocated in TurboFan.

BUG=

Review URL: https://codereview.chromium.org/1066843005

Cr-Commit-Position: refs/heads/master@{#27643}

TBR=mstarzinger@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1064133002

Cr-Commit-Position: refs/heads/master@{#27642}

Review URL: https://codereview.chromium.org/1067933002

Cr-Commit-Position: refs/heads/master@{#27641}

Don't create local branches or otherwise manipulate the
checkout. This reads refs from remote branches and
reads file contents using show. It is faster and requires
less bootstrapping and cleanup.

TBR=tandrii@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/1060013003

Cr-Commit-Position: refs/heads/master@{#27640}

The ES6 grammar forbids the initialization of variable declarations in IterationStatements.

This CL will report `for (var x = y in z)` as a SyntaxError in strict mode (as done in JSC). It is possible that this could break sites in sloppy mode, and so that change can wait.

BUG=
R=
LOG=N

Review URL: https://codereview.chromium.org/1033823002

Cr-Commit-Position: refs/heads/master@{#27639}

Also wrap templates.js in an IIFE to avoid unnecessary pollution
of the builtins object.

Review URL: https://codereview.chromium.org/1067903004

Cr-Commit-Position: refs/heads/master@{#27638}

R=ulan@chromium.org
BUG=chromium:473307
LOG=yes

Review URL: https://codereview.chromium.org/1068833002

Cr-Commit-Position: refs/heads/master@{#27637}

R=titzer@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1065983002

Cr-Commit-Position: refs/heads/master@{#27636}

BUG=

Review URL: https://codereview.chromium.org/1066873002

Cr-Commit-Position: refs/heads/master@{#27635}

Port 146598f4

Original commit message:
Optimistically pushing a lot of arguments can run into the stack limit of the process, at least on operating systems where this limit is close to the limit that V8 sets for itself.

BUG=chromium:469768
LOG=y

Review URL: https://codereview.chromium.org/1066843003

Cr-Commit-Position: refs/heads/master@{#27634}

This enables eager optimization of top-level code with TurboFan and
extends test coverage by triggering it with the --always-opt flag.
Script contexts are now also properly allocated in TurboFan.

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/1053063003

Cr-Commit-Position: refs/heads/master@{#27633}

BUG=
TBR=verwaest@chromium.org

Review URL: https://codereview.chromium.org/1068723006

Cr-Commit-Position: refs/heads/master@{#27632}

Thanks to some careful assumptions, we can examine the object found at
vector[slot] and trust it's a heap object where the second field is
either a map if it's a WeakCell, or definitely not a map if it's a
Symbol, String or FixedArray. Use this to save a memory read.

BUG=

Review URL: https://codereview.chromium.org/1032163002

Cr-Commit-Position: refs/heads/master@{#27631}

BUG=

Review URL: https://codereview.chromium.org/1057613003

Cr-Commit-Position: refs/heads/master@{#27630}

R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/1060683003

Cr-Commit-Position: refs/heads/master@{#27629}

Revert of CpuProfiler: public API for deopt info in cpu profiler. (patchset #6 id:150001 of https://codereview.chromium.org/1045753002/)

Reason for revert:
[Sheriff] Breaks compile here:
http://build.chromium.org/p/client.v8/builders/V8%20Win32%20-%20nosnap%20-%20shared/builds/6115

Original issue's description:
> CpuProfiler: public API for deopt info in cpu profiler.
>
> BUG=chromium:452067
> LOG=n
>
> Committed: https://crrev.com/baf927ff5115ec62a6dad684b9232ed9d3960e3a
> Cr-Commit-Position: refs/heads/master@{#27626}

TBR=alph@chromium.org,jkummerow@chromium.org,svenpanne@chromium.org,yurys@chromium.org,loislo@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:452067

Review URL: https://codereview.chromium.org/1062053004

Cr-Commit-Position: refs/heads/master@{#27628}

BUG=chromium:469768
LOG=n

Review URL: https://codereview.chromium.org/1061263003

Cr-Commit-Position: refs/heads/master@{#27627}

BUG=chromium:452067
LOG=n

Review URL: https://codereview.chromium.org/1045753002

Cr-Commit-Position: refs/heads/master@{#27626}

Instead, please use v8::Isolate::RequestInterrupt to synchronize
to the main thread.

R=yurys@chromium.org
API=Removed v8::Debug::DebugBreakForCommand
LOG=Y

Review URL: https://codereview.chromium.org/1036863002

Cr-Commit-Position: refs/heads/master@{#27625}

Support sxtb and sxth extend operators on add and subtract, as we've
done for ubtx/h. This is similar to ARM support for sxtab/h.

BUG=

Review URL: https://codereview.chromium.org/1064813003

Cr-Commit-Position: refs/heads/master@{#27624}

This reverts commit cbfcee55.

BUG=

Review URL: https://codereview.chromium.org/1051233002

Cr-Commit-Position: refs/heads/master@{#27623}

In case the v8 revision in chromium was set to an older
revision that's not in the list of recent v8 releases, the
script will bail out too early. This changes iterates over
10 more revisions, which should cover all exceeding revisions
in branch period.

NOTRY=true
TBR=hablich@chromium.org

Review URL: https://codereview.chromium.org/1067793002

Cr-Commit-Position: refs/heads/master@{#27622}

R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/1059903004

Cr-Commit-Position: refs/heads/master@{#27621}

This CL primarily makes the loop peeling algorithm more robust; it no longer damages the graph if the loops are improperly closed.

R=bmeurer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1052753004

Cr-Commit-Position: refs/heads/master@{#27620}

BUG=v8:3608
R=yangguo@chromium.org
LOG=y

Review URL: https://codereview.chromium.org/966653002

Cr-Commit-Position: refs/heads/master@{#27619}

We can use xorps/xorpd on Intel CPUs to flip the sign bit. Ideally we'd
use an absolute 128-bit constant in the code object, as OCaml/GCC
does, however that requires 128-bit alignment for code objects,
which is not yet implemented. So for now we materialize the mask
inline.

As drive-by-fix, don't hardcode xmm0 as scratch double register.

R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/1064833002

Cr-Commit-Position: refs/heads/master@{#27618}

The motivation is that we prefer to avoid creating internal properties, and we have a usable field on maps ("transitions", which is not used for prototype maps).
This CL also ensures the invariant that prototype maps are never shared, even if they are in dictionary mode.

Review URL: https://codereview.chromium.org/1033653002

Cr-Commit-Position: refs/heads/master@{#27617}

Revert of Turn off overapproximation of the weak closure again (patchset #1 id:1 of https://codereview.chromium.org/1050443002/)

Reason for revert:
this indeed drops the max major gc time considerable, so turn it back on

Original issue's description:
> Turn off overapproximation of the weak closure again
>
> As long as we still have to process global handles, the impact is not
> yet worthwhile
>
> BUG=v8:3862
> R=hpayer@chromium.org
> LOG=y
>
> Committed: https://crrev.com/294cdc6aecbd7f76be68217da4b3d35901ebce4b
> Cr-Commit-Position: refs/heads/master@{#27570}

TBR=hpayer@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:3862

Review URL: https://codereview.chromium.org/1068723003

Cr-Commit-Position: refs/heads/master@{#27616}

R=mstarzinger@chromium.org
BUG=chromium:469480
LOG=N

Review URL: https://codereview.chromium.org/1034173002

Cr-Commit-Position: refs/heads/master@{#27615}