NumericTextField no longer loses its top and bottom borders when sized shorter than 32 points

NumericTextField lost its top and bottom border when the control was sized shorter than about 32 points tall — for example a height of 26, which matches the height of other single-line controls such as TextField and ComboBox. The left and right border segments stayed visible, so the field appeared as two vertical lines with no frame. This affected both the visual designer and running apps.

The border now stays inside the control bounds at any height, so NumericTextField can be sized to match neighbouring controls.