using width for calculating margin top percent
using width for calculating margin top percent

Summary:
In Yoga, margin is not calculated correctly when defined in terms of percentage at one place.
According to CSS docs , margin percentage should be calculated according to width of container's block in case of horizontal writing mode. (https://fburl.com/5imus0it)
We were using height of container causing some issues in both android and iOS.

## Changelog:

[Yoga] [Fixed] - margin if defined in percentage should use container's width in horizontal writing mode

Reviewed By: alickbass

Differential Revision: D18395285

fbshipit-source-id: 87ebd013e3cba36da45f6548e4dff1bce69cce9b

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