Unreviewed.

        Tighten SheriffBot's flaky test detector
        https://bugs.webkit.org/show_bug.cgi?id=37063

        Instead of just looking for two sequential red builds, look for two
        sequential failures of the same test.  This should reduce sheriffbot
        false positive substantially.

        I'm landing this change unreviewed because I've noticed SheriffBot
        triggering a lot more false positives now that we've expanded the set
        of core builders.  I've tried to take Eric's comments on Bug 37063 into
        account.  I'm happy to iterate on this patch tomorrow once Eric wakes
        up.

        * Scripts/webkitpy/common/net/buildbot.py:
        * Scripts/webkitpy/common/net/buildbot_unittest.py:
        * Scripts/webkitpy/tool/commands/queries.py:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@57065 268f45cc-cd09-0410-ab3c-d52691b4dbfc