This enables adding more language modes in the future.

For maximum flexibility, LanguageMode is a bitmask, so we're not restricted to
use a sequence of language modes which are progressively stricter, but we can
express the language mode as combination of features.

For now, LanguageMode can only be "sloppy" or "strict", and there are
STATIC_ASSERTS in places which need to change when more modes are added.

LanguageMode is a bit like the old LanguageMode when "extended" mode was still
around (see https://codereview.chromium.org/8417035 and
https://codereview.chromium.org/181543002 ) except that it's transmitted through
all the layers (there's no StrictModeFlag).

BUG=

Review URL: https://codereview.chromium.org/894683003

Cr-Commit-Position: refs/heads/master@{#26419}

Port 64f81870

BUG=

Review URL: https://codereview.chromium.org/885283008

Cr-Commit-Position: refs/heads/master@{#26418}

Port 6f97a494

BUG=

Review URL: https://codereview.chromium.org/895243002

Cr-Commit-Position: refs/heads/master@{#26417}

Fixes tree closure caused by r26415

BUG=v8:3502
R=arv@chromium.org
LOG=N

Review URL: https://codereview.chromium.org/869773005

Cr-Commit-Position: refs/heads/master@{#26416}

Applies to API implementation of O.p.toString

- Removes special handling of non-string @@toStringTag values (use builtinTag)
- Removes special handling of @@toStringTags which match [[Class]] names (remove ~ prefix)
- Add tests for non-string @@toStringTag values in test-api.cc

BUG=v8:3502
R=arv@chromium.org
LOG=N

Review URL: https://codereview.chromium.org/892393003

Cr-Commit-Position: refs/heads/master@{#26415}

The Ast Call node is accustomed to using a vector IC slot for the
cases when it uses a CallIC. The super constructor work alters this
somewhat by using a CallConstructStub instead, however the
CallConstructStub expects a vector slot and not a vector ic slot.
This distinction needs to be maintained because slots and ic slots
have different clearing strategies and are handled differently.

R=dslomov@chromium.org
BUG=
LOG=N

Review URL: https://codereview.chromium.org/892113002

Cr-Commit-Position: refs/heads/master@{#26414}

BUG=chromium:449291
LOG=n
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/898753003

Cr-Commit-Position: refs/heads/master@{#26413}

context.

BUG=v8:3629
LOG=N

Review URL: https://codereview.chromium.org/879273004

Cr-Commit-Position: refs/heads/master@{#26412}

- Removes special handling of non-string @@toStringTag values (use builtinTag)
- Removes special handling of @@toStringTags which match [[Class]] names (remove ~ prefix)

BUG=v8:3502
R=arv@chromium.org
LOG=N

Review URL: https://codereview.chromium.org/895633004

Cr-Commit-Position: refs/heads/master@{#26411}

Related to crbug/454297.

Review URL: https://codereview.chromium.org/897523003

Cr-Commit-Position: refs/heads/master@{#26410}

R=arv@chromium.org,rossberg@chromium.org
BUG=v8:3834
LOG=N

Review URL: https://codereview.chromium.org/867153003

Cr-Commit-Position: refs/heads/master@{#26409}

BUG=

Review URL: https://codereview.chromium.org/898783002

Cr-Commit-Position: refs/heads/master@{#26408}

R=verwaest@chromium.org
BUG=454625
NOTREECHECKS=true

Review URL: https://codereview.chromium.org/892833003

Cr-Commit-Position: refs/heads/master@{#26407}

R=bmeurer@chromium.org
TEST=cctest/test-run-jsexceptions/Throw

Review URL: https://codereview.chromium.org/896783002

Cr-Commit-Position: refs/heads/master@{#26406}

BUG=454625
LOG=y

Review URL: https://codereview.chromium.org/900553003

Cr-Commit-Position: refs/heads/master@{#26405}

If a (pure) node has two or more uses, but there exists a path from the
common dominator of these uses to end, which does not contain a use,
then we split the node such that no unnecessary computation takes place.
Note however, that this only applies if the node cannot be hoisted out
of a loop.

BUG=v8:3864
LOG=n
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/899433005

Cr-Commit-Position: refs/heads/master@{#26404}

R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/896463004

Cr-Commit-Position: refs/heads/master@{#26403}

Reason for revert:
Broke compilation on component build http://build.chromium.org/p/client.v8/builders/V8%20Win32%20-%20nosnap%20-%20shared/builds/5007/steps/compile/logs/stdio

Original issue's description:
> Add WeakMap to v8.h
>
> A new map wich references its keys weakly is added to v8.h. Internally it uses the same storage as JSWeakMap but doesn't depend on the JavaScript part of WeakMap implementation in weak-collection.js, hence it can be instantiated without entering any context.
>
> BUG=chromium:437416
> LOG=Y
>
> Committed: https://crrev.com/37d4c57630636f21e3add8d3d1c7c978ff5fc8e0
> Cr-Commit-Position: refs/heads/master@{#26401}

TBR=jochen@chromium.org,mstarzinger@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:437416

Review URL: https://codereview.chromium.org/898763002

Cr-Commit-Position: refs/heads/master@{#26402}

A new map wich references its keys weakly is added to v8.h. Internally it uses the same storage as JSWeakMap but doesn't depend on the JavaScript part of WeakMap implementation in weak-collection.js, hence it can be instantiated without entering any context.

BUG=chromium:437416
LOG=Y

Review URL: https://codereview.chromium.org/886473005

Cr-Commit-Position: refs/heads/master@{#26401}

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/896653008

Cr-Commit-Position: refs/heads/master@{#26400}

R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/886313006

Cr-Commit-Position: refs/heads/master@{#26399}

R=titzer@chromium.org,jarin@chromium.org
TEST=cctest/test-run-jsexceptions

Review URL: https://codereview.chromium.org/873423004

Cr-Commit-Position: refs/heads/master@{#26398}

Cr-Commit-Position: refs/heads/master@{#26397}

BUG=v8:3629
LOG=N

Review URL: https://codereview.chromium.org/898723002

Cr-Commit-Position: refs/heads/master@{#26396}

BUG=

Review URL: https://codereview.chromium.org/885763004

Cr-Commit-Position: refs/heads/master@{#26395}

Review URL: https://codereview.chromium.org/880043003

Cr-Commit-Position: refs/heads/master@{#26394}

For exception in promise we generate v8::Message API object from exception object. And in cases of Syntax or Reference Error we don't have enough information in exception object - we can't restore Error location from top stack frame.
In this patch three aditional private fields introduced for exception object. In case of Syntax Error we store line, column and script on Exception object and receive this information when restoring message.

BUG=443140
LOG=Y
R=yurys@chromium.org

Review URL: https://codereview.chromium.org/885043002

Cr-Commit-Position: refs/heads/master@{#26393}

BUG=

Review URL: https://codereview.chromium.org/894123002

Cr-Commit-Position: refs/heads/master@{#26392}

Both SameValue and SameValueZero consider different NaNs equal, so we
better assign the same hash value to all NaNs.

BUG=v8:3859
LOG=y
R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/897593002

Cr-Commit-Position: refs/heads/master@{#26391}

BUG=450960
LOG=n

Review URL: https://codereview.chromium.org/858213003

Cr-Commit-Position: refs/heads/master@{#26390}

BUG=
R=danno

Review URL: https://codereview.chromium.org/892223002

Cr-Commit-Position: refs/heads/master@{#26389}

Port 246a749a

BUG=v8:3663
LOG=N

Review URL: https://codereview.chromium.org/881533004

Cr-Commit-Position: refs/heads/master@{#26388}

[turbofan] Put StructuredGraphBuilder out of its misery and merge its remnants back into the AstGraphBuilder.

R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/894073002

Cr-Commit-Position: refs/heads/master@{#26387}

BUG=v8:3663
LOG=N

Review URL: https://codereview.chromium.org/879333005

Cr-Commit-Position: refs/heads/master@{#26386}

BUG=v8:3629
LOG=N

Review URL: https://codereview.chromium.org/892213003

Cr-Commit-Position: refs/heads/master@{#26385}

Port 16843e23

Original commit message:
When --vector-ics is true, we still tail-call to the hand-written
megamorphic KeyedLoadIC (formerly "generic"). Now that this code uses
the megamorphic cache, it needs to deal properly with the vector and
slot registers. Achieve this with a sentinel vectors/slot combo.

BUG=

Review URL: https://codereview.chromium.org/894053002

Cr-Commit-Position: refs/heads/master@{#26384}

Cr-Commit-Position: refs/heads/master@{#26383}

R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/889383002

Cr-Commit-Position: refs/heads/master@{#26382}

When --vector-ics is true, we still tail-call to the hand-written
megamorphic KeyedLoadIC (formerly "generic"). Now that this code uses
the megamorphic cache, it needs to deal properly with the vector and
slot registers. Achieve this with a sentinel vectors/slot combo.

R=dcarney@chromium.org
BUG=

Review URL: https://codereview.chromium.org/892173002

Cr-Commit-Position: refs/heads/master@{#26381}

BUG=454091
LOG=Y

Review URL: https://codereview.chromium.org/895573002

Cr-Commit-Position: refs/heads/master@{#26380}