As of https://tc39.es/ecma262/#sec-yearfromtime, YearFromTime(t) should
return `y` such that `TimeFromYear(YearFromTime(t)) <= t`. This wasn't
held, since the approximation contained decimal digits that would nudge
the final value in the wrong direction.
Adapted from Kiesel:
6548a85743
Co-authored-by: Linus Groh <mail@linusgroh.de>
This fixes all failing Date.UTC test262 tests, which failed due to not
handling invalid input and evaluating inputs out of order. But this also
avoids using timegm(), which doesn't work on macOS for years before 1900
(they simply return -1 for those years).
Partially addresses #4651. Date.parse.js still fails.
