Take into account the interruption of the set of tests.

  * Is possible that the set of tests don't finishes. This can happen
    because the bot died when running the tests, or because it reached
    the maximum number of failures or timeouts, so it exits early.

  * So, if the set of test hasn't finished correctly on a revision,
    and we have no specific data for a tests, we should assume unknown
    instead of noerror.
Add a new feature to check on svn.webkit.org when the test was added.

  * Enable the new feature by default (can be disabled with --nochecksvn).

  * The interval printed now starts when the test was added.
    This gives results much cleaner and less confusing.
Make "--showexpected" option the default
Update results for bot "GTK Linux 64-bit Release (Tests)" up to r169605