Summary:
update creation logic for text shadow: allow shadows with zero offset when the radius is nonzero
(?should we also add a check to drop the node as a no-op when color.alpha == 0 ?)
Reviewed By: yungsters
Differential Revision: D10017778
fbshipit-source-id: 0168ac6db5ad22a5d7eb32dcd184aede361d6651