Intent to prototype and ship: Iterator Chunking

[Daniel Minor]

As of Firefox 154, I intend to turn Iterator chunking on by default. It has been developed behind the javascript.options.experimental.iterator_chunking preference. Our implementation was contributed by a volunteer, meg387, thanks Meg!

Summary:

This adds a new Iterator.prototype.chunks and Iterator.prototype.windows methods that allows consume an iterator as either overlapping or non-overlapping subsequences of configurable size.

Bug to turn on by default:
https://bugzilla.mozilla.org/show_bug.cgi?id=2047997

Specification:
https://tc39.es/proposal-iterator-chunking/

Standards Body:
TC39

Platform Coverage:
All

Preference:

javascript.options.experimental.iterator_chunking

DevTools Bug:
N/A

Extensions Bug:
N/A

Use Counter:
N/A

Standards-Positions Discussion:
N/A

Other Browsers:

• Blink, in progress, tracked by https://issues.chromium.org/issues/504663595.
• Safari, in progress, tracked by https://bugs.webkit.org/show_bug.cgi?id=303246

web-platform-tests:
Covered by Test262, the tests haven't been merged yet (https://github.com/tc39/test262/pull/5011), I'll make sure that we have a local copy of the PR that our implementation passes as a part of shipping.