Summary:
Use double for YGRoundValueToPixelGrid calculations as we were losing some precision in float operations
#Changelog:
[Internal][Yoga] Use double for YGRoundValueToPixelGrid calculations
Reviewed By: astreet
Differential Revision: D18225999
fbshipit-source-id: 69c05f56a0e0f3433bf0bd958aa07d26dd83fe02