test: add test cases to test-marshal.js for records

[warner]

This exercises the current behavior of records, both empty objects (with and
without a Far marking), and objects that contain data and/or methods.

It also checks that Far/Remotable can be serialized and passes the
mustPassByPresence() check.

first step of #2018

[michaelfig]

It also checks that Far/Remotable can be serialized and passes the
mustPassByPresence() check.

Why does it do that? The point of the WeakMap is to guarantee that Remotables don't need to be further checked: if they are marked, they are handled specially.

[michaelfig]

It also checks that Far/Remotable can be serialized and passes the mustPassByPresence() check.

If you want to get rid of the special handling and explicitly check the Remotable's contents every time with code, you'll have to avoid adding the prototype to a Remotable. Please don't special-case prototypes, Symbol.toStringTag or toString.

That will be a regression in the debugging experience, and the REPL will have to change as well to print Remotables better.

[warner]

Given the understanding achieved today in #2018 (comment) , I'll change this to remove the mustPassByReference(remotable) tests, as the current code does not attempt to make that claim (even though liveslots was assuming it did). That test can return when I make the changes described in the 2018 comment, and we stop using an inserted prototype to provide the debugging information.

[erights]

Hi @warner I reassigned this to me and just reconciles with #2361 . I cannot add you as a reviewer but please review anyway. Thanks.

[FUDCo]

Seems fine.