Predator try bot

Predator try bot is a service running on Google Compute Engine. Try bot is using the clusterfuzz reproduce tool to reproduce a crash on chrome revisions.

Try bot has 2 methods to find a culprit for clusterfuzz, one way is to verify suspected cls provided by Predator using heuristic rules, if there is no culprit in the suspected cls, Try bot will do bisect on the regression range.