Disable ParserSync test for now, it takes waaaaay too long.

Running this in x64.release mode on a powerful HP620 takes 4 seconds,
this is at least 2 orders of magnitude too slow and leads to tons of
false positives on our build bots due to timeouts. As it is, the
cost-benefit ratio is far too low.

The whole approach needs to be changed: Instead of trying to exhaust
some search space in unit tests, this should be turned into a fuzzing
test where only a small but random number of things are tested. The
exhaustive approach can be done separately, but definitely not in the
unit tests.

BUG=v8:3707

Review URL: https://codereview.chromium.org/762743002

Cr-Commit-Position: refs/heads/master@{#25510}
Mark slow tests as slow.

TBR=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/755283004

Cr-Commit-Position: refs/heads/master@{#25511}
Double timeout for slow tests.

TBR=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/752733003

Cr-Commit-Position: refs/heads/master@{#25512}
[arm] Fix recognition of VNEG.

TEST=mjsunit,unittests
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/762493006

Cr-Commit-Position: refs/heads/master@{#25513}
Revert of [arm] Fix recognition of VNEG. (patchset #3 id:40001 of https://codereview.chromium.org/762493006/)

Reason for revert:
Breaks arm compilation.

Original issue's description:
> [arm] Fix recognition of VNEG.
>
> TEST=mjsunit,unittests
> R=svenpanne@chromium.org
>
> Committed: https://chromium.googlesource.com/v8/v8/+/2aed882fe74dbf9210159babe30fedccd900e7cf

TBR=svenpanne@chromium.org,bmeurer@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/751653004

Cr-Commit-Position: refs/heads/master@{#25514}
[arm] Fix recognition of VNEG.

TEST=mjsunit,unittests
R=svenpanne@chromium.org

Committed: https://chromium.googlesource.com/v8/v8/+/2aed882fe74dbf9210159babe30fedccd900e7cf

Review URL: https://codereview.chromium.org/762493006

Cr-Commit-Position: refs/heads/master@{#25515}
harmony-scoping: make assignment to 'const' a late error.

Per TC39 Nov 2014 decision.

This patch also changes behavior for "legacy const": assignments to sloppy const in strict mode is now also a type error. This fixes v8:2243 and also brings us in compliance with other engines re assignment to function names (see updated webkit test), but might have bigger implications.
That change can easily be reverted by changing Variable::IsSignallingAssignmentToConst.

BUG=v8:3713,v8:2243
LOG=N

Review URL: https://codereview.chromium.org/749633002

Cr-Commit-Position: refs/heads/master@{#25516}
[turbofan] Recognize rotate right.

Extended the rotate left detection code.

BUG=

Review URL: https://codereview.chromium.org/760523004

Cr-Commit-Position: refs/heads/master@{#25517}
Don't use ConsStringIterator to compute string hashes

R=yangguo@chromium.org

BUG=

Review URL: https://codereview.chromium.org/762773002

Cr-Commit-Position: refs/heads/master@{#25518}
Introduce legacy const slots in correct context.

R=rossberg@chromium.org
BUG=chromium:410030
LOG=Y

Review URL: https://codereview.chromium.org/756293004

Cr-Commit-Position: refs/heads/master@{#25519}
Stage ES6 block scoping.

R=rossberg@chromium.org
BUG=v8:2198
LOG=Y

Review URL: https://codereview.chromium.org/751503004

Cr-Commit-Position: refs/heads/master@{#25520}
[turbofan] Implement jump threading after register allocation.

R=dcarney@chromium.org
BUG=

Review URL: https://codereview.chromium.org/754843002

Cr-Commit-Position: refs/heads/master@{#25521}
Fix Windows 32.

TBR=dcarney@chromium.org
BUG=

Review URL: https://codereview.chromium.org/755323007

Cr-Commit-Position: refs/heads/master@{#25522}
Some micro-optimizations in the scheduler.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/764533003

Cr-Commit-Position: refs/heads/master@{#25523}
Make GCTracer not reentrant.

BUG=

Review URL: https://codereview.chromium.org/754023003

Cr-Commit-Position: refs/heads/master@{#25524}
Reuse CFGBuilder in the scheduler to save memory.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/755353003

Cr-Commit-Position: refs/heads/master@{#25525}