Fixing clang-tidy warning.

Bug: v8:8015
Change-Id: Ifb940f40d4145a6074702a3d870242aeca625d96
Reviewed-on: https://chromium-review.googlesource.com/1224092Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Florian Sattler <sattlerf@google.com>
Cr-Commit-Position: refs/heads/master@{#55913}

We really want to catch such errors. (std::optional throws an
exception in some of these cases.)

Change-Id: I7f8c3aff38aed1b3cbe52bcfb92062268fd3b201
Reviewed-on: https://chromium-review.googlesource.com/1177387Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55158}

This is a reland of baa055c7

Original change's description:
> Applied noexcept to all mctors and massigns
> 
> Refactoring the code base to use noexcept for their move constructors and move
> assignment operators.
> 
> Bug: v8:7999
> 
> Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
> Change-Id: I13d24eddba3bfa601cff26fd680a040cf4e71426
> Reviewed-on: https://chromium-review.googlesource.com/1152817
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Marja Hölttä <marja@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Commit-Queue: Florian Sattler <sattlerf@google.com>
> Cr-Commit-Position: refs/heads/master@{#54841}

Bug: v8:7999
Change-Id: I72394e326a4f8da462ee6285511d721440ceb21d
Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
Reviewed-on: https://chromium-review.googlesource.com/1158646Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Florian Sattler <sattlerf@google.com>
Cr-Commit-Position: refs/heads/master@{#54863}

This reverts commit baa055c7.

Reason for revert: mips compile failure: https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8%20Mips%20-%20builder/18458

Original change's description:
> Applied noexcept to all mctors and massigns
> 
> Refactoring the code base to use noexcept for their move constructors and move
> assignment operators.
> 
> Bug: v8:7999
> 
> Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
> Change-Id: I13d24eddba3bfa601cff26fd680a040cf4e71426
> Reviewed-on: https://chromium-review.googlesource.com/1152817
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Marja Hölttä <marja@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Commit-Queue: Florian Sattler <sattlerf@google.com>
> Cr-Commit-Position: refs/heads/master@{#54841}

TBR=marja@chromium.org,yangguo@chromium.org,ahaas@chromium.org,jgruber@chromium.org,sattlerf@google.com

Change-Id: I49757025daac368a647887a63164e927f0106803
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7999
Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
Reviewed-on: https://chromium-review.googlesource.com/1158644Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54843}

Refactoring the code base to use noexcept for their move constructors and move
assignment operators.

Bug: v8:7999

Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I13d24eddba3bfa601cff26fd680a040cf4e71426
Reviewed-on: https://chromium-review.googlesource.com/1152817Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Florian Sattler <sattlerf@google.com>
Cr-Commit-Position: refs/heads/master@{#54841}

This allows base::nullopt to be used instead of base::Optional<Foo>()
and implicit conversion to Optional<T> from T.

Also added NOLINT comments to the implicit constructors.

Change-Id: I4c688045685e2a50e0c0d38a959570f77454ec61
Reviewed-on: https://chromium-review.googlesource.com/893268Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51003}

base::Optional is a replacement for std::optional, until we switch to
C++17 and can use std::optional directly.
The implementation is copied from chromium's base::Optional, but put in
the {v8::base} namespace instead of just {base}. Also, the
specialization of std::hash for base::Optional is omitted, since it's
disallowed in the style guide.

A first use in the AsmJsParser is introduced, if that one sticks, I
will refactor more uses of std::unique_ptr to use base::Optional
instead, avoiding the heap allocation.

R=mstarzinger@chromium.org
BUG=v8:6474

Change-Id: I019599d4bf9ff0105bf592dfb96d6050feba18ae
Reviewed-on: https://chromium-review.googlesource.com/528884
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45810}