unclamped method
Reverses the effect of one call to clamp() (assuming clamp() didn't return null). If clamp() succeeds, range.clamp(...).unclamped() == range.
If this range isn't clamped, it is returned unchanged.
Multiple chained calls to clamp() require the same number of calls to unclamped() to undo.
Implementation
DatepickerDateRange unclamped() => this;