Fix rerun barrier for flaky tests.

- The rerun flag doesn't include the first run.
- Timeout is an int. The division makes it 0 for small
numbers.

BUG=374134
LOG=n
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/364793007

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22172 ce2b1a6d-e550-0410-aec6-3dcde31c8c00