Summary:
@public The current CSSLayout can't support RTL because wrong calculation for absolute position.
This change is mainly to fix the issue: https://github.com/facebook/css-layout/issues/197
Three main problems I fixed:
1. Calculate the position in the same way as margin, boarder, and padding. So that to fix the absolute problem.
2. Fix one wrong calculation for leading value when we only know the trailing value. It was hard code for the LTR situation. Now I changed it to depends on the main Axis.
3. Expose getter and setter function for RN to read layout direction and start/end position value.
Reviewed By: fkgozali
Differential Revision: D3616949
fbshipit-source-id: ae7a47cc0a5d02b42b95f87232be51ab144056d9
