deps: add back no-op harmony shipping flags

[ofrobots]

Checklist

• make -j4 test (UNIX), or vcbuild test nosign (Windows) passes
• commit message follows commit guidelines

Affected core subsystem(s)

deps:v8

Description of change

This PR adds back the shipping harmony flags (i.e. no-ops) that were removed in V8 5.1. While uses of V8 flags is generally not supported by Node, in this case a trivial change reduces minor hardship in the ecosystem by adding back these flags (and making them do nothing).

Fixes: #8388
Ref: #8395
R=@nodejs/v8
EDIT: CI: https://ci.nodejs.org/job/node-test-pull-request/3967/
CI: https://ci.nodejs.org/job/node-test-pull-request/4033/
V8-CI: https://ci.nodejs.org/view/All/job/node-test-commit-v8-linux/310/

[addaleax]

LGTM pending green CIs… thanks for putting this together!

[MylesBorins]

LGTM

tested locally to confirm that the noop flags work as expected

[ofrobots]

Note that I have not added back the --harmony_modules flag. It was removed in V8 5.1, but it was not a 'shipping', but rather an 'in progress' feature. Since modules require embedder support anyway, I don't think much, if anything, is dependent on that flag.

[jasnell]

This LGTM for v6, but I want to make sure it's absolutely clear that these won't be in v7. We should likely have a documented policy that V8 flags removed within a major would only be noop'ed in that major, and removed completely in the next major.

[evanlucas]

LGTM. Thanks @ofrobots!

[ofrobots]

We should likely have a documented policy that V8 flags removed within a major would only be noop'ed in that major, and removed completely in the next major.

I think our policy should be that use of V8 flags is not supported. This is a one-off change, and not intended to set precedent that we want to be playing with V8 flags.

[ofrobots]

@bnoordhuis you had left a -1 on #8395 on the idea of floating a patch. Would you be okay with this change?

[targos]

LGTM

[bnoordhuis]

A grumbling LGTM.

[ofrobots]

Thanks. Landed on v6.x-staging as 9c460d7.