Text layout includes trailing whitespace when wrapping center/right justified text

We try and perform the same wrapping behavior as word processors and generally avoid trailing whitespace when measuring for wrapping, but the justification code is still treating it as significant.

1. Create a text layout with wrapping enabled.
2. Enter some text so that it wraps.
3. Change the justification to right aligned.
4. Observe the trailing whitespace on the wrapped line is included in the justification.