Since the bug fixed the month-year picker behavior and now the datepicker does not offer an out-of-range month/years, and the input's max/min handling is tracked by the bug 1613280
Bug 1501987 Comment 5 Edit History
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Since the bug 1676068 fixed the month-year picker behavior and now the datepicker does not offer an out-of-range month/years, and the input's max/min handling is tracked by the bug 1613280, maybe this bug could be closed now?