[v18.x] backport various patches of internal refactorings for snapshot and realms

[joyeecheung]

This backports various refactoring patches for snapshot and shadow realms support to smooth out the backports of other patches. AFAICT only the shadow realms support patch changes the behavior a bit (but only if users uses the --experimental-shadow-realms flag and we don't have any compatibility guarantee for that anyway).

src: add initial shadow realm support

Add initial shadow realm support behind an off-by-default flag
--experimental-shadow-realm.

PR-URL: #42869
Refs: #42528
Reviewed-By: Antoine du Hamel duhamelantoine1995@gmail.com
Reviewed-By: Darshan Sen raisinten@gmail.com

src: per-environment time origin value

According to https://html.spec.whatwg.org/#environment-settings-object,
the timeOrigin is a per-environment value. Worker's timeOrigin is the
time when the worker is created.

PR-URL: #43781
Reviewed-By: Matteo Collina matteo.collina@gmail.com
Reviewed-By: Anna Henningsen anna@addaleax.net
Reviewed-By: Paolo Insogna paolo@cowtech.it
Reviewed-By: Joyee Cheung joyeec9h3@gmail.com

src: fix cppgc incompatibility in v8

This patch updates the layout of the BaseObjects to make sure
that the first embedder field of them is a "type" pointer, the
first 16 bits of which are the Node.js embedder ID, so that
cppgc will always skip over them. In addition we now use this
field to determine if the native object should be interpreted
as a Node.js embedder object in the serialization and deserialization
callbacks for the startup snapshot to improve the reliability.

Co-authored-by: Joyee Cheung joyeec9h3@gmail.com
PR-URL: #43521
Reviewed-By: James M Snell jasnell@gmail.com
Reviewed-By: Darshan Sen raisinten@gmail.com

bootstrap: check more metadata when loading the snapshot

This patch stores the metadata about the Node.js binary
into the SnapshotData and adds fields denoting how the
snapshot was generated, on what platform it was
generated as well as the V8 cached data version flag.
Instead of simply crashing when the metadata doesn't
match, Node.js now prints an error message and exit with
1 for the customized snapshot, or ignore the snapshot
and start from scratch if it's the default one.

PR-URL: #44132
Reviewed-By: Anna Henningsen anna@addaleax.net
Reviewed-By: Chengzhong Wu legendecas@gmail.com

src: iterate over base objects to prepare for snapshot

Instead of iterating over the bindings, iterate over the base
objects that are snapshottable. This allows us to snapshot
base objects that are not bindings. In addition this refactors
the InternalFieldInfo class to eliminate potential undefined
behaviors, and renames it to InternalFieldInfoBase.
The {de}serialize callbacks now expect a InternalFieldInfo struct
nested in Snapshotable classes that can be used to carry
serialization data around. This allows us to create structs
inheriting from InternalFieldInfo for Snapshotable objects
that need custom fields.

PR-URL: #44192
Refs: #37476
Reviewed-By: Anna Henningsen anna@addaleax.net
Reviewed-By: Chengzhong Wu legendecas@gmail.com

src: support WeakReference in snapshot

Move util::WeakReference to a separate header and implement
{de}serialization for it to be snapshotable.

PR-URL: #44193
Refs: #44014
Refs: #37476
Reviewed-By: Matteo Collina matteo.collina@gmail.com
Reviewed-By: Chengzhong Wu legendecas@gmail.com

src: introduce node::Realm

To distinguish per-context values from the node::Environment, split
those values to a new node::Realm structure and consolidate
bootstrapping methods with it.

PR-URL: #44179
Refs: #42528
Reviewed-By: Joyee Cheung joyeec9h3@gmail.com
Reviewed-By: James M Snell jasnell@gmail.com

src: create BaseObject with node::Realm

BaseObject is a wrapper around JS objects. These objects should be
created in a node::Realm and destroyed when their associated realm is
cleaning up.

PR-URL: #44348
Refs: #42528
Reviewed-By: Joyee Cheung joyeec9h3@gmail.com

src: refactor BaseObject methods

• Wrap the initialization of the kSlot and kEmbedderType fields
  into a BaseObject::SetInternalFields() method.
• Move the tagging of kEmbedderType field into
  BaseObject::TagNodeObject()
• Add a variant of BaseObject::MakeLazilyInitializedJSTemplate()
  that only needs IsolateData.
  This makes it easier to create BaseObject subclasses.

PR-URL: #44796
Reviewed-By: Chengzhong Wu legendecas@gmail.com
Reviewed-By: James M Snell jasnell@gmail.com

benchmark: add vm context global proxy benchmark

PR-URL: #44796
Reviewed-By: Chengzhong Wu legendecas@gmail.com
Reviewed-By: James M Snell jasnell@gmail.com

vm: make ContextifyContext a BaseObject

Instead of adding a reference to the ContextifyContext by using
a v8::External, we make ContextifyContext a weak BaseObject that
whose wrapper is referenced by the sandbox via a private symbol.
This makes it easier to snapshot the contexts, in addition to
reusing the BaseObject lifetime management for ContextifyContexts.

PR-URL: #44796
Reviewed-By: Chengzhong Wu legendecas@gmail.com
Reviewed-By: James M Snell jasnell@gmail.com

[nodejs-github-bot]

Review requested:

• @nodejs/gyp
• @nodejs/http2
• @nodejs/net
• @nodejs/startup

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/47324/

[joyeecheung]

cc @legendecas @nodejs/releasers

[legendecas]

Thanks for doing the backports!

[joyeecheung]

Added back some changes to test/pummel/test-heapdump-env.js that were left out

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/47493/

[mcollina]

lgtm

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/47592/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/47619/

[joyeecheung]

Landed in 0774b64...c37dc7c

[danielleadams]

#43781 was dropped from v18.13.0 (#46025) because it is semver-major change - if its decided that this is a bugfix for v18.x, we can open another backport and drop the semver-major label.