Reviewed by Eric Seidel.

        Expose more more failure information from Buildbot to SheriffBot
        https://bugs.webkit.org/show_bug.cgi?id=46697

        This patch moves the information about what tests failured closer to
        SheriffBot.  There are still a couple more patches to go before
        SheriffBot can post this information to bugs, but this is a step in
        that direction.  Yay for unit tests, which caught some bugs in earlier
        versions of this patch.

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

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@68492 268f45cc-cd09-0410-ab3c-d52691b4dbfc