In RTL, while editing a number field, the negative sign is on the incorrect side

[ericrosenbaum]

Expected Behavior

The negative sign should always appear on the correct side while typing in a number.

Actual Behavior

In RTL, while editing a number, the negative sign incorrectly appears on the right side. Once the edit is accepted, the negative sign moves to the correct side (after #1702):

In a report from an educator for the Perisian language, this bug results in young people thinking they need to type 10- in order for it to display correctly. Then the value is wrong and doesn't do what they expect.