Opt state takes a GP instead of a GeometryStage

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/71856d520461ae025a0332aa0ce9735a096d9baf

Review URL: https://codereview.chromium.org/637003003
bug_chomper: Use parenthesized declaration style for const and vars.

It seems cleaner that way and nicer to read, also avoids repeating
'const' and 'var' everytime you have to add more items.

BUG=None
TEST=./run_server.sh
R=borenet@google.com

Review URL: https://codereview.chromium.org/645803003