[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}