spline is cut off with when axis.y.padding is 0

A spline chart with `axis.y.padding` set to 0 will be cut off:


When the `y` axis shows a percentage, I would like to avoid padding since it introduces y ticks > 100.

A line chart of the same data does not have this problem:


It would be nice if the spline chart could be padded just enough to fit the spline but without introducing new ticks on the y axis.

Start by reproducing a spline chart with axis.y.padding set to 0, then compare its rendering with the equivalent line chart using the issue's examples. Trace the spline chart's y-axis and curve bounds; done means the spline is not clipped while the axis avoids introducing ticks above 100%.1

Written by the indexing model from the issue text.