Bug 275489 – [JSC] Fix `Intl.DurationFormat` for `numeric` and `2-digit`

• Status: RESOLVED
• Resolution: FIXED
• Component: Layout and Rendering

[Sosuke Suzuki]

In the current JSC `Intl.DurationFormat` implementation, only units with a value that is not 0 or a
    display setting that is not `auto` are formatted. However, this behavior is incorrect according to
    the current spec[1]. When a unit's style is `numeric` or `2-digit` (i.e., the unit is `hours`,
    `minutes`, or `seconds`), it needs to be formatted even if its value is 0 and its display is set to
    auto. For example, consider the following code:
    
    ```
    const df = new Intl.DurationFormat("en", { hours: "numeric", minutesDisplay: "auto", secondsDisplay: "auto" });
    print(df.format({ hours: 0, minutes: 0, seconds: 1 }));
    ```
    
    This code is expected to output `0:00:01`, but the current JSC outputs `0, 01`. Only the hours and
    seconds are displayed, while the minutes are not. Additionally, the separator `:` is not used; instead,
    `,` is outputted.
        
    [1]: https://tc39.es/proposal-intl-duration-format/#sec-partitiondurationformatpattern

[Sosuke Suzuki]

Pull request: https://github.com/WebKit/WebKit/pull/29823

[Radar WebKit Bug Importer]

<rdar://problem/130279541>

[EWS]

Committed 280460@main (471838036efe): <https://commits.webkit.org/280460@main>

Reviewed commits have been landed. Closing PR #29823 and removing active labels.