Setup for -Fast GCE bot.

I'd like a bot that has got optimization turned up to 11,
to let us test things that our Chrome-like bots normally can't.

(Not quite ready to commit this bot to -ffast-math yet.)

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1704473002

Review URL: https://codereview.chromium.org/1704473002
3 files changed