Stop closing filled paths in GrShape

This can force a copy of the path data and isn't really being taken advantage of. It complicates a forthcoming change to key small paths based on their data rather than gen id.
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2355833002

Review-Url: https://codereview.chromium.org/2355833002
1 file changed