Because ECMA262 5.1th section 220.127.116.11-10 `TimeClip(UTC(finalDate))`, [[PrimitiveValue]] of Date object created by Date Constructor relys on current Timezone.
test cases are failed at some Timezone which is not GMT+8 such as JST-9.
Does the test probe for timezone handling/dst? If not, I think Date.UTC() would be a better choice.
Some countries have predictable dst settings, others have government-made rules for it, which are not known for future dates without patches.
Created attachment 26
rev1: Adjust to UTC8
I've created patch to adjust Date result to UTC8.
Since tested dates in these cases are not in range of DST, I think simple timezone shift code is enough for this.