Bug 275745 – [JSC] `Intl.DurationFormat` nfOptions.roundingMode for seconds / microseconds / nanoseconds should be "trunc"

• Status: RESOLVED
• Resolution: FIXED
• Component: Images

[Sosuke Suzuki]

```
const duration = {
  seconds: 1,
  milliseconds: 500,
};

function sameValue(a, b) {
  if (a !== b) {
    throw new Error(`expected ${b} but got ${a}`)
  }
}

const df = new Intl.DurationFormat("en", { seconds: "numeric", fractionalDigits: 0 });

sameValue(df.format(duration), "1"); // but got "2" since we use "rounding-mode-half-up"

```

[Radar WebKit Bug Importer]

<rdar://problem/130771643>

[Sosuke Suzuki]

Pull request: https://github.com/WebKit/WebKit/pull/31477

[EWS]

Committed 281955@main (55784d54785e): <https://commits.webkit.org/281955@main>

Reviewed commits have been landed. Closing PR #31477 and removing active labels.