Normative: Add Temporal[@@toStringTag].

[Ms2ger]

Fixes #1539.

[codecov]

Codecov Report

Merging #1541 (c740827) into main (828dd2f) will decrease coverage by 3.92%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1541      +/-   ##
==========================================
- Coverage   95.02%   91.09%   -3.93%     
==========================================
  Files          19       17       -2     
  Lines       10778    10774       -4     
  Branches     1725     1608     -117     
==========================================
- Hits        10242     9815     -427     
- Misses        523      943     +420     
- Partials       13       16       +3     

Flag	Coverage Δ
test262	?
tests	90.15% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
polyfill/lib/now.mjs	100.00% <100.00%> (ø)
polyfill/lib/plaindate.mjs	72.06% <0.00%> (-18.31%)	⬇️
polyfill/lib/plaintime.mjs	79.72% <0.00%> (-11.03%)	⬇️
polyfill/lib/plainmonthday.mjs	83.56% <0.00%> (-9.59%)	⬇️
polyfill/lib/zoneddatetime.mjs	90.62% <0.00%> (-7.77%)	⬇️
polyfill/lib/instant.mjs	87.15% <0.00%> (-7.30%)	⬇️
polyfill/lib/timezone.mjs	86.27% <0.00%> (-7.19%)	⬇️
polyfill/lib/plaindatetime.mjs	90.34% <0.00%> (-6.97%)	⬇️
polyfill/lib/plainyearmonth.mjs	89.77% <0.00%> (-6.63%)	⬇️
polyfill/lib/duration.mjs	93.65% <0.00%> (-4.43%)	⬇️
... and 5 more

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[ptomato]

I will mark this as "draft" so it's not accidentally merged before being presented to plenary.

[ptomato]

If we go with Temporal.now[@@toStringTag] as discussed on #1539 then this PR will need to be updated.

[ptomato]

I believe this is covered by the consensus achieved at the July 2021 TC39 meeting as part of the "Guidance on nested namespaces" item. I will add the updates to Temporal.Now as per that item and un-draft this.

[justingrant]

Does this change need to be ported to @js-temporal/polyfill? shim.js doesn't exist over there because that polyfill doesn't (yet) put itself in the global namespace, so I wasn't sure how this PR fits in to it, if at all.

[Ms2ger]

Temporal is a module namespace object in that context, I think, and it might not be possible to put a Symbol on there. We'll need to figure out how / if we want to support exposing the object on the global object there.