Revert of Introduce a kill-switch for shipping features. (patchset #2 id:20001 of https://codereview.chromium.org/763273002/)

Reason for revert:
Reverted for breaking nosnap: http://chromegw.corp.google.com/i/client.v8/builders/V8%20Linux%20-%20nosnap/builds/1003/steps/Check/logs/Threading3

Original issue's description:
> Introduce a kill-switch for shipping features.
>
> R=rossberg@chromium.org
>
> Committed: https://chromium.googlesource.com/v8/v8/+/d6285620868b15c84eb9affa59f6b4e869f074b8

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

Review URL: https://codereview.chromium.org/763353002

Cr-Commit-Position: refs/heads/master@{#25574}

R=rossberg@chromium.org,caitpotter88@gmail.com
LOG=Y

Review URL: https://codereview.chromium.org/768833002

Cr-Commit-Position: refs/heads/master@{#25573}

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/756073004

Cr-Commit-Position: refs/heads/master@{#25572}

BUG=v8:3292
R=yangguo@chromium.org, wingo@igalia.com
LOG=N

Review URL: https://codereview.chromium.org/760303002

Cr-Commit-Position: refs/heads/master@{#25571}

R=rossberg@chromium.org

Review URL: https://codereview.chromium.org/763273002

Cr-Commit-Position: refs/heads/master@{#25570}

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/767733002

Cr-Commit-Position: refs/heads/master@{#25569}

TEST=mjsunit/numops-fuzz-part4
BUG=
R=balazs.kilvady@imgtec.com

Review URL: https://codereview.chromium.org/756073003

Cr-Commit-Position: refs/heads/master@{#25568}

R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/768763002

Cr-Commit-Position: refs/heads/master@{#25567}

R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/757813003

Cr-Commit-Position: refs/heads/master@{#25566}

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/752263003

Cr-Commit-Position: refs/heads/master@{#25565}

BUG=

Review URL: https://codereview.chromium.org/766663006

Cr-Commit-Position: refs/heads/master@{#25564}

This switches off the resources feature. It will be solely
used for configuring files to be copied to android devices
in a follow up CL.

TBR=svenpanne@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/764013002

Cr-Commit-Position: refs/heads/master@{#25563}

R=yangguo@chromium.org
LOG=N

BUG=437280

Review URL: https://codereview.chromium.org/769453002

Cr-Commit-Position: refs/heads/master@{#25562}

R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/762123002

Cr-Commit-Position: refs/heads/master@{#25561}

BUG=417668
LOG=n

Review URL: https://codereview.chromium.org/750813003

Cr-Commit-Position: refs/heads/master@{#25560}

TBR=svenpanne@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/722023006

Cr-Commit-Position: refs/heads/master@{#25559}

NOTRY=true
BUG=chromium:431669
LOG=n
TBR=jkummerow@chromium.org
TEST=./script_test.py

Review URL: https://codereview.chromium.org/765943002

Cr-Commit-Position: refs/heads/master@{#25558}

TBR=rossberg@chromium.org

Review URL: https://codereview.chromium.org/762083002

Cr-Commit-Position: refs/heads/master@{#25557}

port c142994f

original commit message:

    Flesh out vector ic state query and set mechanisms.

    The IC system now fully integrates the vector concept and can
    handle loads and keyed loads vector-based.

BUG=

Review URL: https://codereview.chromium.org/763953002

Cr-Commit-Position: refs/heads/master@{#25556}

R=rossberg@chromium.org,arv@chromium.org
BUG=v8:3330
LOG=N

Review URL: https://codereview.chromium.org/766663003

Cr-Commit-Position: refs/heads/master@{#25555}

Port c142994f

Original commit message:
The IC system now fully integrates the vector concept and can
handle loads and keyed loads vector-based.

BUG=
R=akos.palfi@imgtec.com

Review URL: https://codereview.chromium.org/752553005

Patch from Balazs Kilvady <balazs.kilvady@imgtec.com>.

Cr-Commit-Position: refs/heads/master@{#25554}

BUG=

Review URL: https://codereview.chromium.org/764803002

Cr-Commit-Position: refs/heads/master@{#25553}

The IC system now fully integrates the vector concept and can
handle loads and keyed loads vector-based.

BUG=
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/754303003

Cr-Commit-Position: refs/heads/master@{#25552}

R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/753073009

Cr-Commit-Position: refs/heads/master@{#25551}

R=caitpotter88@gmail.com
BUG=v8:3502
LOG=N

Review URL: https://codereview.chromium.org/764823002

Cr-Commit-Position: refs/heads/master@{#25550}

Previously, a separate string to be hashed (in order to help determine the need to
use a cached Template Call Site) was built up by joining UTF8 spans within a template.

Now, the hash key is generated from the original spans, removing the need to allocate a new
buffer and copy bytes into it.

BUG=

Review URL: https://codereview.chromium.org/765473006

Cr-Commit-Position: refs/heads/master@{#25549}

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/761143002

Cr-Commit-Position: refs/heads/master@{#25548}

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/750333003

Cr-Commit-Position: refs/heads/master@{#25547}

BUG=

Review URL: https://codereview.chromium.org/765773002

Cr-Commit-Position: refs/heads/master@{#25546}

Re-land: Distinguish beween final incremental mark-compact and full mark-compact event in IdleNotification.

BUG=
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/765743002

Cr-Commit-Position: refs/heads/master@{#25545}

BUG=

Review URL: https://codereview.chromium.org/733893003

Cr-Commit-Position: refs/heads/master@{#25544}

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/761673004

Cr-Commit-Position: refs/heads/master@{#25543}

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/761733002

Cr-Commit-Position: refs/heads/master@{#25542}

Port 6ac4de87

Original commit message:
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/766703002

Cr-Commit-Position: refs/heads/master@{#25541}

With this flag, we grow if more than 10% survived the last scavenge.

BUG=none
R=hpayer@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/753543002

Cr-Commit-Position: refs/heads/master@{#25540}

BUG=

Review URL: https://codereview.chromium.org/763063002

Cr-Commit-Position: refs/heads/master@{#25539}

Still requires changes to gyp files to select the built-in clang as
compiler and make clang the default on the platforms we want it.

BUG=
R=dcarney@chromium.org,machenbach@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/745963005

Cr-Commit-Position: refs/heads/master@{#25538}

a revival of https://codereview.chromium.org/467013003

R=rossberg@chromium.org

BUG=

Review URL: https://codereview.chromium.org/760883002

Cr-Commit-Position: refs/heads/master@{#25537}

R=rossberg@chromium.org, yangguo@chromium.org
LOG=Y

Review URL: https://codereview.chromium.org/761913002

Cr-Commit-Position: refs/heads/master@{#25536}

BUG=chromium:436816
LOG=N

Review URL: https://codereview.chromium.org/765473004

Cr-Commit-Position: refs/heads/master@{#25535}