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>